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Bultaco 350 Clutch Troubles


trialsrfun
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I have now ridden a trial on my recently restored Bultaco 350 model 199a the blue one but find the clutch take-up too sharp.

It has the all metal clutch the plates appear to be flat & in good condition not blued or burred on the tangs, everything seems ok, the clutch does not slip but take up is sharp making bike control difficult also it does not clear very well making it very difficult to select neutral with the engine running.

Has anyone any ideas has I have tried everything that I can think of without success & this problem is spoiling what is otherwise a very nice bike to ride.

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I have a similar problem with my 199A-getting neutral after a stop with the engine running. I have a set of Barnett clutch plates, good springs, correct rod/ball and believe it or not have spent some time with a dial guage and spring adjustment to get the clutch plates running true. Even the clutch pivot rod ( the vertically mounted object that moves the rod in the cases) is new.

Clutch take up is fine- but the neutral problem persists. My local Bultaco guy wants me to go back to standard bar levers-not the short ones I run-for motre travel.

Has anyone had experience with the Clutch kit offered by Phalfer from Germany

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Although there is no perfect answer there is alot to help that you can do. New or very well oiled cable, shorten the cable so that it works over tangent of the pull rather than before, I have used the longer brake arm which givesa little more leverage. Good tqf, greased rod ball and even drill and fit grease nipple to the casing were the rod is pushed all help. Biggest benefit I found though was fitting frontera plates and then back off the springs till the clutch slips then tighten back down a little from there. Never used a dial gauge found it better to spin the clutch round and then using the lever see if the clutch expands straight then adjust to suit.

Hope this helps, a while since I did mine but the hours are etched in the memory. :hyper:

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Bike is fitted with Domino dog leg levers (like fantic etc have) I too thought that maybe they did not pull sufficient cable so I tried about three types of lever including the Amal type that were fitted as standard.

No one lever seemed to make any difference though.

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Not being able to select neutral is usualy caused by clutch drag. All Bultaco clutch's drag (Fact) but this can be reduced by carefull set up.

Some people recommend using Pursang clutch plates (or Frontera they are the same) but in my experiance this is not neccessary.

I always run my clutches with one plate less than fitted originally (the last plate, the one just under the outer spring plate. Not sure if this makes a big difference but I tried it years ago and it seemed to improve things and have never fitted this last plate to a clutch since.

All the previous advice about cable condition and arm operating levers is the place to start as if these are not in good condition or set up correctly you are wasting your time. Also new springs are a good idea with these matched for length as best as possible.

I adjust the nuts so that the thread is protruding just beyond the nut and then pull in the clutch lever and hold in this position with a cable tie on the lever and handlebar. With the clutch held pulled in I then rotate the clutch via the kickstart and carfully adjust each spring adjuster until clutch plate wobble is either totally eliminated or at least reduced to the absolute minimum possible. The nuts should have about 1 to 1.5mm thread protruding. Don't forget to secure the nuts with some locking wire.

Finally I replace the primary case cover and fill with 300cc of ATQF. This is what I used back in the 70's when the bikes were new. You can not teach an old dog new tricks!

The older bikes do not have adjuster nuts but use a non adjustable pin and cup arrangement. My Model 80 (1971) with new springs and the one plate removed will slip the clutch with a sharp kick from the kickstater when cold but a smooth follow through kick will get her going and she never gives a problem when warmed up or actually slipping when riding.

Twinnshock

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Slightly off topic!

I have been asked to put a set of new plates in a friends Pursang to cure the clutch slip. Last night when taking the clutch apart I got a bit concerned with the amount of up and down movement. Bottom line is the gearbox main shaft (and clutch pushrod) has snaped in half!

We have been riding this bike in this condition.

Twinnshock

Edited by twinnshock
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I have now stripped, thoroughly cleaned & checked all the clutch parts as well as the operating lever in the mag case, nothing appears to be worn or damaged.

Pushrod is straight, ball bearing ok as is the mushroom & thrust race, handlebar lever & cable are fine.

All the plates were laid flat on plate glass & all but 3 seemed perfectly flat, the other 3 maybe a thin feeler gauge blade could be slid between the clutch plate & the glass, does this mean that they should be replaced or would such a small amount of uneveness not matter.

I do have the longer (front brake arm fitted) to make the clutch lighter to operate I think this is fitted as suggested.

Everything is back together for now following the above advise with good tqf in, clutch action is a little better though take up is still a little bit harsh & neutral is sometimes possible to find, much easier than before to ride (though any worse & it would have been unrideable) should the 3 plates be replaced or left alone or do all the lot need renewing.

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The distortion on the three plates is about 3 to 5 thou measured with a feeler gauge blade from the plate glass.

Am unfamiliar with this type of clutch with all steel plates and as these have slots etc cut into them I suppose there will be a degree of flex when under spring pressure but if this distortion is sufficient to cause trouble then I had better get replacements.

Thank you all for the help.

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Nigel I renewed the primary chain & tensioner during the recent overhaul, springs are all exactly the same length & the clutch basket is in really good condition as is most everything else. When the clutch was put back together again particular care was taken (following the advice given here)to get the same amount sticking out on the threads when the springs were tightened up & to get an even release on the pressure plate.

Is it typical of this type of clutch to be sharper on take up than one with mixed type plates.

Going off it a bit the engine pulls amazingly well from nothing at all & the gear ratios & overall gearing seem just about right for most anything I have yet ridden. My mate rides an SWM Rotax 280cc I think, the Bult is sharper with more pull but the Rotax is very very smooth & forgiving & gets the job done very well, both bikes handle very similarly with a sort of indistinct sense of direction presumably due to not having much fork trail (leading axle, fork legs & steering stem not parallel) as yet we cannot say which bike might grip the best, weight feels much the same.

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  • 2 weeks later...

Have fitted the clutch plates (all the same way sharp edge out) & spent ages carefully setting the pressure plate using the cable tie method & having test ridden it it seems much better ( I felt in control ?) but will let you know after the next trial hopefully soon.

Thanks for all the advice.

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I have had the same problem with the clutch take up being too sharp on my 340 Sherpa 199B. I have tried everything, but have now bought a set of Barnett composite clutch plates from the USA to replace the original all steel ones. I have not used the bike with them in yet as I'm currently rebuilding the engine. I will be trying it out at the weekend.

Has anyone else tried the Barnett plates?

post-13-1119371260.jpg

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