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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
 Posted - 07 Feb 2008 : 2:49:46 PM
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Hi All,
Can anyone advise of a good sealer to use with copper head gaskets, methanol compatible? I have tried a spray on copper type with no success, it is quickly reduced to liquid, resulting in leaks.
A friend suggested something called "Dirko 036131", but I am finding it impossible to get. Any clues? |
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john
Forum Moderator
Victoria
3130 Posts |
Posted - 07 Feb 2008 : 8:36:58 PM
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| Three Bond |
John Daley Sidecar #68
' there are those who do, those who dont do and those who undo. We must lampoon the latter." |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 08 Feb 2008 : 10:04:48 AM
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Thanks John, what grade (eg product code)?
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David
Site Administrator
Australia
999 Posts |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 20 May 2008 : 09:13:53 AM
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Hi All,
Has been a while since the last update. I have been busy making the last round of changes to the saga and hoping that this will be it for a while!
The latest developments have included:
12:5.1 pistons
Kevlar Clutch
Kibblewhite spring kit
Revised porting
Reprofiled cam and re-welded rockers
Lightened crank
The budget is expended for the saga now! Hopefully it will all hang together, will be nice to know that I have completed the "full race kit" on the engine now.
For your viewing pleasure, a picture of the lightend crank and new pistons alongside the standard crank and pistons is below. Quite a difference! Thanks for converting the picture David.
I am hoping to complete the disk brake conversion in the next year or so: I am not out braking the T500 brake just yet so it can wait a little while until I am, and the budget allows!
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Edited by - Ben on 20 May 2008 4:38:57 PM |
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GD66
Senior Member
Western Australia
390 Posts |
Posted - 20 May 2008 : 7:03:53 PM
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| Woo-hoo, nice one, Ben, looks great and they're all good mods, good to see you've hung in there and kept a development curve happening for The Saga, should be a good fun little weapon by the time you get it all locked away. Eddie Preston is making noises about us doing the long drive over for the Southern Classic at Broadford again, if he does so I hope to be back over there as well to catch up once again for a top race (and bench racing) weekend, look forward to catching up with all the Club K4 reprobates.... |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 22 May 2008 : 08:21:42 AM
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Thanks GD, yes will be good to finally have it sorted! Has been slow development, but thankfully K4 riders are a giving bunch and have helped greatly in developing the right way.
There will be a nice field of K4s at the S/C if you can attend! I'll keep my eye out for you. PM me your race number/mobile number so I can find you.
Cheers,
Ben. |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 27 Jan 2009 : 08:23:42 AM
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Hi All,
What a disaster PI 2009 was! (this seems to be a pattern with PI..... maybe its just not for me...).
Went out for first practice and got a few trouble free and slow running in laps in, bike was feeling strong. Out for practice number 2, 2nd lap, just winding it up onto the straight when....CLUNK..... rattle...... CLUTCH IN!!!!!
Coasted into the pits and peeked into the exhaust - chunks of metal are surely not a good sign ..... spark plug out then.....mmmmmm, electrode belted in....... piston top missing..... exhaust valve head missing........
What the?
Insert Image:
59.41 KB
Sat still for a while and tried not to look at the bike.
Pulled it apart last night to view the full extent of bad news........Bad indeed...... camshaft snapped in half, right side combustion chamber and cylinder sleeve ruined, my very nice piston belted beyond recognition with the culprit still present (note exhaust valve head still embedded in piston).
The whole top end will need to be replaced/rebuilt..........I can see the saga being out of action for some time.
Am baffled - all clearances were good, plenty of valve to piston/piston to head/valve to valve clearance - could be one of two things - 1. Cam snapped and locked valve in place to receive a ruthless bashing from piston. 2. Faulty valve dropped its head.
Any thoughts?
A picture is included for your enjoyment (thanks David)................. Back to the drawing board...... and on the phone trying to find parts.....cylinder head anyone?
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Edited by - Ben on 27 Jan 2009 11:20:52 AM |
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john
Forum Moderator
Victoria
3130 Posts |
Posted - 27 Jan 2009 : 11:26:16 AM
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| Did you get the cam shaft crack tested? |
John Daley Sidecar #68
' there are those who do, those who dont do and those who undo. We must lampoon the latter." |
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OldKwak
Level 2 Member
Victoria
156 Posts |
Posted - 28 Jan 2009 : 10:52:26 AM
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| Interesting, Adrian in our pit was running a 250 and snapped two cams at PI - is this an omen? |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 28 Jan 2009 : 3:51:43 PM
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Crack testing may be a good idea......
Omen? Yes, possibly that PI is a crazy track to belting historic bikes around!! knock a kilometre off the circuit for historics perhaps.....
This was a a cb250 cam.....Omen indeed. Where did the ones Adrian snapped break? Any clues as to why?
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OldKwak
Level 2 Member
Victoria
156 Posts |
Posted - 30 Jan 2009 : 2:55:24 PM
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His broke right next to the cam wheel, the same is yours seem to have. One was an aftermarket hot cam the other a standard road cam.
One theory is that he may not have got the correct width bearings at each end thus providing a little less support and that the flexing in the middle was enough to fatigue the cams until they gave up.
pb
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GD66
Senior Member
Western Australia
390 Posts |
Posted - 30 Jan 2009 : 5:49:54 PM
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| Not so sure of that, Oldkwak. I would have thought having a needle roller conversion on each end of the cam would have been a better bet under racing conditions than the original alloy endcaps, which are prone to wearing and ovalising under continued high-speed use. In saying that,in 2003 Brett Eaton's Honda, a real jet from the workshop of Ian Johnson the kiwi wizard, also broke a cam in the centre. You'd have to ask Keith if one of Ed's has ever done so. But mine, which has a needle roller conversion, has been over there three times and never missed a beat, and certainly never had any cam issues. It could be just old-fashioned crappy bad luck on Ben's behalf.The thing is, you can't just have the cam rolling left and right freely in the needle rollers, or it will shave and then kick out the left end seal....has to be shimmed to reduce endplay... BTW Oldkwak, are you saying your garage buddy is racing a modded CB250 in postclassic ? |
Edited by - GD66 on 30 Jan 2009 5:54:08 PM |
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OldKwak
Level 2 Member
Victoria
156 Posts |
Posted - 31 Jan 2009 : 1:12:07 PM
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GD66, I think you may have proved the point, if you look closely at Ben's photo it will reveal a ball bearing NOT a needle roller as you have in yours. Adrian had a Ball Bearing setup, same as Ben's and it is indeed possible that the ball bearing may not provide enough support. In any case its only a theory. But to have two machines break three camshafts between them in almost the same place is the equivalent of me winning tattslotto 5 times in a row. I don't think its just bad luck but someone doing something wrong, like using the wrong bearing type. I do agree that the mod is necessary over stock.
Yes, he said it was a 250 |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 01 Feb 2009 : 3:12:37 PM
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Interesting indeed. The 6004 bearing conversion has been done by many for many years with good results, it is from memory what Ed L runs in his K4 and Matcho Mick in his. I would put it down to bad cams, fatigued or just plain cracked......... an odd coincidence though! Crap bearings could be another explanation.... bloody bikes eh? I would think that after this, if running the 6004 conversion, a new rocker box is also in order as it is very likely that the ends in which the bearings sit would be stretched.
Lucky, that is one of the spares I actually have!
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Edited by - Ben on 01 Feb 2009 7:32:45 PM |
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peen0_0
Level 3 Member
Victoria
224 Posts |
Posted - 13 Mar 2009 : 09:53:02 AM
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Ben, not sure if this is of any use to you, or your 350 colleagues? In searching through my parts bin recently, I have come across what appears to be a 350 twin cam and other bits. Is it of any use? I'll be at the Vic Historics if you want to have a look.
You'll know us, we are on the "Pink Pig" sidecar 20.
Cheers, Tony. |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 13 Mar 2009 : 10:13:47 AM
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quote:
Originally posted by peen0_0
Ben, not sure if this is of any use to you, or your 350 colleagues? In searching through my parts bin recently, I have come across what appears to be a 350 twin cam and other bits. Is it of any use? I'll be at the Vic Historics if you want to have a look.
You'll know us, we are on the "Pink Pig" sidecar 20.
Cheers, Tony.
Thanks Tony, always interested in new bits for the saga. Would be pleased to take a look, I'll be there on the Saturday. Might be a cb450? |
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matcho mick
Advanced Member
New South Wales
570 Posts |
Posted - 15 Mar 2009 : 10:27:46 PM
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wonder if it's anything to do with reground cams,mine is factory RSC,is actually a "fat" cam,with centres i ground down for lightness,concidering,#1 i've locked the motor with bent valves through ingested pit gravel,#2 engaged 2nd instead of 4th at (my) max revs (no tacho,change when sensing valve bounce approaching  ),& cam has survived all this mistreatment for quite some time,god knows how many years before i inherited it too,soo can we find out if these cams that broke were indeed regrinds??,i know yours was Ben,how about Adrians?,Old Kwak any thoughts??,cheers Mick |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 16 Mar 2009 : 09:31:13 AM
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Good thought Mick, that was what I thought initially, then talked myself out of it as the cam was reprofiled by a reputable cam grinder and surely they would not leave a cam too brittle after welding.....
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 01 Apr 2009 : 09:58:42 AM
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Hi All,
Does anyone have a race profile cam that they are not using/is gathering the dusts of time that they would be willing to sell to me for the saga rebuild? Any top end parts also considered if you have some (basically need everthing)...
Thanks. |
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peen0_0
Level 3 Member
Victoria
224 Posts |
Posted - 01 Apr 2009 : 5:12:07 PM
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Ben, I won't be at the Historics after all, but will keep those parts aside for when we might be able to catch up.
Chjeers, Tony. |
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racer7
Level 2 Member
67 Posts |
Posted - 12 May 2009 : 6:51:27 PM
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Hi All
Re-reading the topic from first to last, we started off with brakes. Whilst re=spoking my disc braked 350 front wheel, a casual visitor to my shed asked why I didn't have the drum brake fitted. After a lengthy explanation, my (now)non friend visitor, just said "Well they used to lap the Isle Of Man at over 100 mph decades ago. And used drum brakes!
I don't like him anymore. 'Cause now I'm putting the 'Drum' back! So many experts, so little time! |
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GD66
Senior Member
Western Australia
390 Posts |
Posted - 13 May 2009 : 10:13:39 PM
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Not on a CB350 twin, they didn't ! Pay no heed. R7, and whack your disc back on. I have a drum (GT750 Suzuki), because when I first built the bike for the 1987 season, I was adamant that it had to "look period". And it does look good, and it stops like hell (right, Sir Al ?). But it still has linings from that time in it, which are so politically-incorrect and carcinogenic they should feature in an X Files episode.....it's a great brake, but for lightness, simplicity and performance, you can't beat a disc.
And for what it's worth, CB350 Hondas now are capable of lapping the Island at over 100 mph....and they're all fitted with discs... |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 04 Aug 2009 : 09:28:53 AM
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Hi All,
Has been a while and will be a while yet (other life priorities draining bike funds!!....), but I am hoping to have the saga back to life by early 2010. I received my long awaited Joy Cam last week and now just need get the new valves and a rebore sorted - the put it all back togther of course.
Not as easy as it sounds at the moment but I remain committed!!
Cheers,
Ben. |
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CB72
Level 2 Member
39 Posts |
Posted - 02 Dec 2009 : 08:35:28 AM
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That valve looks like it snapped off at the spot where the head is welded to the stem. Was it a one piece valve or Honda supplied two part valve?
We run our CB160 based racers up to very high revs and have been luck until last summer when the rider tried to chase down a CB350 up the long main straight. I heard the slight miss at the very top end that's a sure sign of valve bounce, and sure as God made little green apples, the head came off on the way to turn five at full tilt in 4th.
Ruined the head, crank, barrels etc etc.
Cam failure was probably caused in this case by the force of smashing the valve through the piston.
Those cams are old and break easily especially with lots of valve lift or if the valves start to float. In fact Megacycle snapped a CB92 cam of mine trying to straighten it to replicate the grind.
Needle rollers or bronze bushes are better at containing whip that ball bearings.
Essentials on a K4 are good valve springs - we use R&D with Titanium top caps and set the spring pressures. Next are good one piece valves and preferably with undercut stems and lightened heads - and replace them often - especially if you miss a shift or over rev it until the valves bounce. |
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GD66
Senior Member
Western Australia
390 Posts |
Posted - 02 Dec 2009 : 7:15:01 PM
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| Wecome aboard, CB72. Do you not find the R and D springs are too high a poundage ? I got a set awhile ago from CAT racing, with some titanium valves, but my engineering guru is reluctant to use them for fear that they'll tulip the valve heads due to their high rate. Your thoughts ? |
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CB72
Level 2 Member
39 Posts |
Posted - 03 Dec 2009 : 05:45:34 AM
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G'day GD.
It's been a while since I checked the seat pressures, but I'd ask your engineer what seat pressure he thinks those valves need and compare that to the actual values. Someone there must have a spring tester and you already may have measured the installed height.
On problem I have is that I pull valves back into the head (pocketing) to get the compression I'm after, so I have to be careful there with all the inherent compromises that entails. That leaves the valve stems taller than stock so I frequently have to use shims or spacers under the springs.
Springs are just another area of compromise. Too soft and valves float. Too hard and it wipes out cams and followers. high lift cams create even higher pressure under load but you don't want to have the seat pressure too low.
If you ever plotted a cam and looked at the acceleration rates you will see that most cams are brutal on valves and seats and they need quite a lot more pressure than a modern 4 valve motor with its light valve gear.
I have used springs from just about every manufacturer over the years and in time they all float and all break - some are worse than others.
That all said, the issue here may be that he thinks that there's too much pressure for a light Titanium valve which has considerably less inertia than a stock or lightened steel valve. In which case it may be possible to cut the spring seats slightly to lower the seat pressure.
Or ask R&D what they recommend for Ti valves.
If your engineer has a spring he likes with enough seat pressure, not too much pressure at full lift and good damping between the coils I'd use that. My favorites were Norris triple wound with a flat damper between the two springs. I have no idea who made them for Norris, but now I use R&D and they work fine.
It all comes down to how hard you rev it and how often you miss gears.
If you short shift an never miss a shift, you can probably use softer springs. I tend to make the motor compensate for my lack of riding skills and work them hard, so I need a little more pressure to hold things together. Stuff wears out so that isn't an issue, but breaking is costly.
I'd be interested to hear your engineer's recommendations or suggestions.
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GD66
Senior Member
Western Australia
390 Posts |
Posted - 03 Dec 2009 : 10:13:48 AM
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| Time will tell.I've got them, so I'm interested in using them. The poms swear by them, and they still have a fairly hot CB350 series going. Guy Martin said they're even using seven-speed boxes in some of the hotrods they have running at the TT and Sothern 100 ! But the CAT racing bike went ok and seemed reliable enough, that was a few years back when Alan Oversby was the pilot. I'll be looking to use that gear when I finally build a metho motor for my old girl, jury's still out on what pistons to use though. Eddie Lauder has had good results with Omega pistons in Keith's bike, there's a set in there that has apparently suffered a couple of blowups and are still in ok nick. J&E will make pistons to suit, some have used Todd Henning/Buff Harsh stuff but had appalling after-sales backup which has limited appeal, so I'm still dithering....need to get it done though, because all tracks still seem to have straights !! The valve springs I have in it have been in so long I can't remember where I sourced them, they're heavier than stock but not by much. Those who use stock don't seem to have any dramas, but as you say, there's always a missed shift waiting out there somewhere... |
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CB72
Level 2 Member
39 Posts |
Posted - 03 Dec 2009 : 4:03:03 PM
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Those Henning pistons are pretty good. I had a pair, but of course they are 67.5mm for AHRMA regs which is slightly O/S but within reason. (not as big as a 44cc BSA 350 or 600cc Manx Norton in the 350 class).
The crown shape is pretty good and is remarkably close to what we run in our CB72, but ours has less of a bump and we machine more off the head and barrel to make it all work.
I like the ring pack that Todd specified. It is the best available.
Omega pistons have a great reputation in the UK, but I have no experience with them.
Stock springs and 12,000 rpm are a disaster waiting to happen. It's only a matter of time.
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 08 Dec 2009 : 7:52:03 PM
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Hi All,
CB72, the valves were APE from the states, one piece units. It was a shame to ruin them as they were lovely valves! I am going to try the needle roller ala GD in the new motor and see how it goes.
Getting there. My new cylinder head is ready with locally made one piece stainless valves and R&D springs w/titanium caps. I had these in the other motor but they did not get much of a run!!
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Topic |
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CB350: The Saga!
