gasgas

Funny Ham2

No 100:1 or 1% isn't too lean for me. When you see my playground you understand why. It is half throttle max riding for only a blip. Richer wld load her up with carbon even more. The most guys are running 1:80 but these bikes use full throttle for longer periods, like hill climbs etc. trailriding i also wld use 1:70-80 for safety precautions although i doubt the necessitty of it, with nowadays synthetics. Just took off the exhaust pipe to have a look at the inside and the full throttle blasting of yesterdays really cleaned things up for the better. Rings look cleaner and the cilinder crosshatch pattern looks cleaner too, and the cilinderhead has some dry carbon now. There is no carbon at the squish at all.(like in the picture on top) Had i cleaned the motor earlier things wld have looked even better, i reckon now. The day before yesterday the cilinderwall was a little brownish glaced and now it looks clean again

yeah, strictly premix here

R2w, looking at yr pictures i reckon you do use full throttle a lot so running a full synthetic suits you Wait, i put a picture of my playground here. To give you guys an impression of my throttle setting as promised....

Hi did a search but cld not find a specific topic about: which two-stroke oil is best in a low revving 18 hp trials engine. We use synthetics a lot which were made for mx racing engine 12.000 and 40 hp, so what made use believe we have to use them also. Lately it got me thinking why a mineral oil for low temp/low stress situation wld not do the job equally good or maybe even better than the full syns. http://www.ultralightnews.com/features/oiltest.htm What do you think about bio-degradable oils for outboards? My cilinderhead fouls up with carbon after only 15/20 hours so i feel i am using the wrong oil. At the moment full synthetic castrol TTS, which works in my mx bike perfect. Any opinions? Pls let me know.

Just an hour ago i ran the bike full throttle a couple of times up the hill, and evently it started smoking out of the exhaust pipe when closing the throttle. I have never seen this with this bike only with my crossbike. Tomorrow i will check the cilinderhead and see what happened there.

guys, very nice replies here. You all more or less express my feelings about why it builds up carbon. Since my bike really runs smooth when warm, without smoking, i feel my air/fuel mix is ok. I ran it 1:100 one whole year with that picture as result, so i feel that it is caused by not running it hot enough so not revving it enough. At this moment it is around 0 degrees celsius overhere, and i am running a 40 pilotjet, so it cld be a little rich although i don't think so. What i will do, is the down the road running, get it really hot and see how that turns out, by again looking tru the exhaust port. Will reply later, how that went. O btw, when did you guys have a peek tru the exhaust to see how yr cilinderheads/cilinders look? And are there more with good results going to a half synthetic 2stroke oil? Maybe there is a gain there also.

Ham2, yes cld be, but i have that covered see my topic:gasgas splitting cases. But, yesterday when i took the exhaust pipe off, and looked tru the port i saw this carbon appearing after only approx 15/20 hours of riding(not in the quantitiy shown here on this pic, but there was already some), so i like to know how many of you did actually have a look into the barrel/head and give some back up.

Rode this bike for one year, new rings/piston, cilinder freshly hooned. lubrication 1% synthetic. Rings were sticking due to carbonised and were not sealing properly. Engine did run oke nevertheless, which is funny. In my area i never use more than half throttle max. Is this picture a normall clinderbowl look due to low throttle for one year.

Let me reply a little further on Jimsshed reply. Just today i checked my piston/rings by looking tru the exhaust opening and to my surprise i noticed quite some carbon built up within 15 hours of slow driving. Especially the cilinderhead was covered with wet/oily carbon, which is the result of my 15 hours of merely slow/idle driving. Here in holland we don't use more than 1/2 throttle. The motor does not become hot enough to cleanly burn all the oil/fuel. So, an old engine, which starts knocking can very well have this problem occuring: carbon build up.

Ahhh finally i can watch some wc indoor, wednesday 19.00 local time. In holland i can not watch eurosport 2.

With a replated cilinder and new piston plus rings the only thing that shld be done is give the piston a few heat cycles. It seems that a new piston expands new differently(faster) as when it is older. Something to do with "molecules". I am not a metallurgisch guy so maybe somebody with knowledge can jump in here. The heat cycles are there to give this piston a few chances to expand and contract again. Further there is nothing to it. Rings are settled in a new cilinder after about 10 hours(i have this info from a man who replated my cilinders and is working for GP teams in sidecross) A new plated cilinder takes even more time to settle. So, it is safe to say that yr motor is up to parr after about 10 hours of riding. That doesn't mean you have to take it slow after the heat cycles, only that yr engine becomes better after 10 hours....

Yeah, guys don't get over exited about a little feel. A mainbearing that goes, will leave a lot of shaking before it really goes. It starts to rumble and shake and you really will feel the difference. A big-end that is going is more difficult to trace however, so check that one regular, like once a year. And when in doubt because you drowned the bike etc and you cld not fix it right away, better shop for a new one, incl mains. The rust will eat it away rapidly. So when yr motor is running normally without more shaking than ussual, ride it.

Neonsurge, although the consensus is no play shld be felt, i can speak out of experience that it is possible to feel play when the there is a slipfit on either the crankjournals and/or cases.With a pressfit you have to be very sentive(like i am) to still feel play, but it is there undetected. When you have fixed the woodruff key and the engine is running see if you have any abnormall behavior. Rev the engine and chop throttle that will give you a good feel if there is anything wrong with the bearings. When you have done all the normall maintenance and never found any sand or such thing behind the filter it is virtual impossible to wreck the mainbearings. Not with a low revving trialsbike anyway. So just check its behavior after you fixed it. Is it still feeling good or not? Edit: ha i was just a little too late with my reply i see.

Nitjay, you can set the comp and extension any way you like. They work loose from each other. My suggestion is, as you said you find them stiff/hard to let some oil out of the tubes/forks as this is probably causing the harsness. Maybe the former owner poured to much oil in the legs. Go to the Gasgasusa page and find the exploded view of the forks. Measure the amount that is coming out and check with the manual how much shld be in there. The comp and extension screws are not so sophiscated in a trials bike. Hence you almost feel nothing at all changing these settings.

Yes, gear oil lubes the mains and at the clutch side they get the full load of particles. Try grabbing the flywheel and really push hard up and down. No, anyway no detectable, movement shld be felt. However 0.01mm more or less is the freeplay of a mainbearing so when in doubt stop driving the bike around and go for a pro to let him feel it. Check out the topic of mine: it is a open Pro 2002 engine. Do a search: Pro engine

Baldilocks has a point here. Maybe something is worn there, making that noise. Mine Pro 250 2002 has a shipped startergear and the tooth was loose in the cases. Made a mess but no serious injurious thnks god. So check the clutch innerside for anything out of order.

I heard the inners do not come out to wash. Can someone pls verify this. Thanks

Yes, wld love to come to Seattle but that distance At my club there is this guy, who is also back in the saddle after 15 years or so. He was 18 when he stopped and now about 34 he is picking it up really fast. It just good to see how quick "old" trialers pick up the pace like they never quit. He won last clubevent after 3 months training. Scary. Enjoy yrslvs again, and hope to see u in amsterdam one time

First Uhoh, Thanks for putting that card on the forum. Now i know what you guys are talking about. Second, since holland never has had a champion , i am not divided by feelings over riders. The best rider wears the krone, he deserves it. The rest are loosers(for that years championship). i think Raga looks very handsome in his dress (do i have bisexual feelings ?) Seen Lampkin i dare to say i won't have the same feelings .(if i were a girl) Ooooo is the card for PR only. Pls erase above statement....

Or you cld make a picture and we comment, if nobody has one. Wiring diagrams are shown on GG Usa i think. try this link http://www.gasgas.com/Pages/Technical/Elec...ing-ducati.html

Uhm, since you put in new slave-piston seals and the problem is still there i wld say pressure leak is at the lever side. Maybe seals are neccessary there also. You say you don't feel a pressure loss, but when you pull in the lever how long will it take before pressure is gone, hence bike is creeping forward?

Don't know exactly what they cost, but one thing i am sure of, they are not built to be serviced That won't stop me though. The whole inner material is steel-wool, and the inner core is wrapped with a sort of braided steel messing(if that is the english word for it?), so next time i just burn the baby clean. What i also did now to be sure. Somebody wants to give a try? Ps:she is now at the welder, as i don't see myself welding this thin steel together.

Sorry i never buy new bikes so i wld not know what is recommened but i can say what i wld do. Since you gonna use it for trail riding a 1:70-80 mix wld do in my opinion. Going a little fatter on the oil first few rides is ok. Just give the pistonrings time to seal properly, normally it takes 5/10 hours before rings seat nicely on a new cilinder. So after two tanks riding the compression shld go up, as motor settles itself. I just rebuilt my GG 250 and one thing i noticed is how rough some components are, so these components will benefit break in. Also change oil after the first ride and monitor it. Greasing all the bearings can't hurt either. I really don't know how well they are lubed ex the factory but seeing yr weather it is a nice job to do during the evenings.

Congratulations you opened that crate quick. And as it seems on the pics front wheel is at the right place