feetupfun

I have just tried another way to make the TXT Boy clutch engage at lower RPM and it works well. Someone in an earlier thread noticed that the parts list for the motor in the trials GG50 lists two clutch springs while the racing GG50 motor lists four springs and they postulated that some GG50 Boys had been fitted with motors with four spring clutches. I have not heard yet of anyone else taking two springs out but it is terrible riding weather here and a long weekend for me so I carefully pulled my son's bike's clutch cover off and had a look. Yes it had four springs and taking two springs out looked simple enough and the design is such that the change in the loading pattern on the pressure plate does not cause any problems so out they came. Amazing, it hooks up nicely a bit above idle now, it does not creep or drag, the manual clutch still works fine and there are no problems putting it in and out of gear with the motor running. Our GG 50 Boy was part of the first shipment of 2011 models to Australia.

The Aussie Trials site is www.trials.com.au here is a link to the forum string about the paint scheme http://www.trials.com.au/content/index.php?option=com_wrapper&view=wrapper&Itemid=7viewtopic.php&p=20898#p20898

Have another look at the Aussie trials site. I have just posted the photos you are thinking of

Before you get the case welded, fix the return stop mechanism or it will do it again. The stop device is on the kickstart shaft and the usual failure mode is that it slips (rotates on the shaft). You can fix it by getting a new kickstart shaft. The weld repair can be made smooth on the outside and can be poilshed but may still remain visible due to the colour of the weld metal being slightly different to the parent metal.

Has anyone yet tried using the standard plates and running with only two springs?

Oh yeah thats right Ross and the Pursang backing plate would need to be sleeved down.

Sorry for saying the obvious but you did not say how you were kicking it. Unless you are very tall, lengthening the kickstart lever will make it hard to get you boot high enough. Doubling the length will mean the end will hit your leg (or worse) If you lower the compression ala 1997 and later Techno motors you will find it easier to kick over compression. The 1994, 1995 and 1996 Technos take a much bigger kick to get over compression than the later (tamer) 97,98,99 model Technos. The suggestion to retard the ignition a bit would also help if you are feeling any kickback. I've never heard of a longer lever that fits the Techno motor and the Beta Rev 3 motors have a very short aluminium lever. Any competent metal fabricator could extend the existing lever if you are certain that is the way for you.

Yes they are all nice and there are no dud models as far as reliability goes. Do remember that the production of Sherpa Ts spanned about 17 years so you can expect that the earliest models will weigh a few kg more and have less ground clearance than the last models. Many technology and design improvements were introduced throughout those years but overall it was gradual evolution not radical change at any stage. To list all the changes over the years would be quite a list. If you are really interested, buy a copy of the book "historia de la sherpa T" by Francois Stauffacher. It is written in Spanish and English, well illustrated and msny of the changes are mentioned. There are quite a few minor detail changes that are not mentioned but the book tries to link changes to model designations, and in many cases the changes were just implemented at the convienience of the manufacturer as they became available, rather than waiting for the next model designation to be made. If you want the most competitive bike, go for the late models. Fortunately not everyone wants the late models so you see people enjoying Sherpa Ts that were made throughout the 17 years. As Dave said if you are heavy and/or ride at very high altitude or only do free riding, the 325 and 340 motors will pull harder than the 250s and 238s. If you are lightweight or not fit and want to compete in trials then the smaller motors will be easier on your body for kickstarting and riding in tight sections.

There are lots of possible causes for a poor spark not just a poor HT coil earth. also consider: Poor stator coil earth Capacitor condition Stator to magnets clearance Stator plate rotated away from ideal position Points dirty/wrong gap Poor connections in wiring Poor earth from motor to frame Leakage to earth via kill switch or points wiring MK8 Pursang front wheel should fit in the front end of a M199A. May need work on axle length, axle spacer and brake stay arm.

Yes the steel sleeves (inner bushes) can wear. They can also rust. With enough time and money, it is possible to convert your 349 to rolling element swingarm bearings but why would you when it is so much easier to just replace whatever is worn?

Stand on the LH side of the bike and kick it with your right leg

Gary I could only find one very dark photo of the LH side of the top of the motor on FB. That photo looks like a Cota 348 motor (310cc and made from 1976 to 1978) David

Yes that looks like the tank from a 348T

Excellent info there. It sounds like the float needle valve is stuck open. Inside the bottom of the carby is a plastic float that opens and closes a valve to control the fuel level inside the bottom half of the carby. The mechanism can sometimes stick with the valve open if the fuel dries out as it would have while you had the bike apart. Diagnosis: Try starting the motor again but as soon as it starts, close the fuel tap and see if the running improves as the fuel in the float bowl is used up. If it does that then you will need to free up the float valve mechanism. On that bike you can do that by taking off one of the frame braces and the top of the carby then rotating the carby so you can take the bottom (float bowl) off. Do the fuel-tap-shut testing first before working on it.

More info needed What do you call bogging What carby Air filter state/condition What jetting Is float valve passing Is it different behaviour hot to cold Has it run well before Is it new to you Are there any changes to inlet tract or exhaust system from standard Whatever other clues you can give

I think that it isn't really the length of the swingarm per se that is important, but that the relationship between the upper run of the chain and the location of the swingarm pivot is important. Changing swingarm length on a bike can affect the geometry of the chain run, and it also changes the fore/aft weight distribution of the bike+rider.

Hi Brian yes I like your M159 too - almost as much as your avatar but I'm sure you didn't look like that when I saw you last Regards David

Be careful with your engine temperature. Wiseco pistons are made of an alloy with a relatively high expansion rate compared with many other pistons. If your machinist has given the Wiseco piston a clearance significantly less than Wiseco recommend (to avoid piston rattle), it will be susceptible to seizure if the motor gets hot.

If it's advice you want you may get help at www.ozvmx.com.au

The actuating lever at the case is completely different (being push from cylinder retaher than pull from cable) but the TY250Z arm and camshaft could be substituted. Not sure if there would be clearance for the cable though due to the location of the exhaust on the Scorpa

The term used for bikes that can be started in gear by pulling in the clutch is "primary kickstart" and has nothing to do with whether the primary drive is by gears or chain or whatever. "Primary kickstart" means that the kickstart turns the clutch basket. "Non-primary kickstart" (Bultaco and many others) means that the kickstart turns the gearbox input shaft.

I have looked at my spare 348 frame for a while with a similar idea, but the problem with the 348 frame is that it relies on the bolt-on braces from swingarm pivot to the head, and the brace from the head to the frame, to provide triangulation for the main frame loop. Depending on the shape of the proposed motor going in, it may be possible to fit braces that will provide triangulation.

It says it in the catalogue what they are (eccentrics for Sachs monoshocks). One is for +/- 3.5mm and another for +/- 2.5mm

Sorry I can't help you yet because I haven't worked on my 2011 Gas Gas Boy 50 yet, but please tell me more about the clutch mod you are about to do. I think the (auto) clutch engages at too high an RPM. I want it to engage at lower RPM. Is that what you are seeking to do also?