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I have a 2000 Gas Gas 200 with probable main bearing damage. Noisy. Radial clearance is not measureable but left and right, axial, dials .012 to .016 inches. Appears the crank is moving in the bearings, or the bearings moving in the cases.
I have heard issues with oil drains, seals installs, etc, but that normally increases the radial clearance also, not?
Will split it soon, but any ideas or prevention of it happening again will be appreciated.
k
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True. I'll have a look at the 175 this weekend. I think the same concept could be used: avoid welding by pivoting the bracket on the axle. Then either take the bracket in one piece up to the bolt lug, or using a torque arm bar up to the bolted lug, similar to the drum.
It sort of defeats the spirit of the twin shock, but the brakes are so much better I would find a way to make it work.
k
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How old and worn out?
If piston clearances are too great, the pistons don't cool properly. This leads to hot piston top and preignition/detonation,. More important in two strokes. Doesn't usually mean hotter running oil in the sump though.
If there is excessive blowby, minimal compression, it will run hot, but seizure is not far behind then.
My bet is restricted exhaust, lean mixture, or timing off. either R or Adv will do it.
Do you have enough oil in the crankcase? Mud in the fins, dragging brakes, the obvious stuff?
k
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I have mounted a late GG wheel and 4 piston disc brake to my TY350. No welding either, I floated the new bracket on the axle hole and took the torque reaction through the original lug on the side of the lower leg.
It works awesome. somewhat stronger, but PRECISE and good feel.
I am pushed for time now, I can send you some pics later. send me an address.
Shoes: I think front Ty twin ;shocks and back TY mono are same, can't recall. Anyway I have bought a lot of shoes trying to find a good combination. (til finally the disk.)
genuine yamaha vaires a lot. I got some NOS yamaha they were great. nex time Yam sent SBS Scnadinavian Braking System shoes. Hard as nails, wore forever, and very little braking.
Vesrah, Japanese, has worked well for me. I get from Dennis Kirk Co. in the US. din't notice where you are.
plan on changing offten. Some cleaners reactwith the resins, lose the friction. Some (like ether starting fluid spray) react and and make the shoes shoe sticky they grab and lock up. Another advantage of the disk.
have to run,
k
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Thought of something else: If it is really bad overfueling, check the o-ring around the center needle jet where it fits into the bowl. On the TK carb, the main jet is in the bowl, removable from outside. That's great, but if the o-ring from needle jet to bowl leaks, the fuel goes around the main jet and on its way.
Usually only shows up as overfueling at mid range or more, but I have seen this issue several times.
k
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tank/seat cover and fender on ebay. for 94 TYZ?
http://cgi.ebay.com/ebaymotors/ws/eBayISAP...&category=34284
k
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Brian:
Dennis Kirk has a list of all the thread sizes they have.
I recently needed a gasgas one. Idnetical to the Yamaha, but opposite hand thread. and not available from Kirk. $32 from GG, so I thought not too bad.
the 6 in one sounds like the best deal.
k
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If you are getting little aluminum balls or specks, its a sign of detonation or preignition or both. melting off the piston and a very bad sign.
as previous post wrote, look for air leaks, too lean, too much advance, bad gas, etc. but deal with it quickly.
kcj
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boofont: thats exactly what I was trying to deal with, I am sure the air bubble was up high in the top of master cylinder.
so, today got it on the hoist, pulled all the plastic, but before I started bleeding it did a check of the pedal. Perfect brake. minimal travel, no spongy, predictable and firm. Put the plastic back on and lower the hoist and ponder why.
todays UCTT is to to nothing and the problem has resolved itself.
Why do I feel its going to reappear at the most inopportune time?
I am thankful it appears solved now.
k
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tks all. will attack again tonight.
Have free play in the lingkage, replenishing port is open, fluid goes back into the reservoir.
Problem seems to be where the hose from caliper makes bend at the swing arm. The high point is in the cylinder, and the blind end of cylinder is higher than either in or out ports. Hence the disassemble and twisting flat (that didn't work).
and yes, chris uk's magic box has crossed my mind a lot.
I need it going for our first event a week away, and found out am leaving town now for the UK, hope to return the night before the trials. son may ride without much rear brake. daughter is set, and at least my old Yam has front disc but cable in back.
i'd love to stay in uk and see a trials over there, but won't see anything except the inside of an engine room.
k
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i wrote a note with my renewal (last year also). They probably have a zillion forms printed and will last forever. Low on the priorities surely. k
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The most discussed curse of the entire trials bike: bleeding rear brakes.
Actually it was a bit spongy, so I was flushing fresh fluid through, then trying to bleed it out better.
96 GasGas. The actuator is at the bottom, so the highest point on the master cylinder bore is above the inlet, and above the outlet.
Done all the basics that are covered on every post: removed pads, shimmed pistons apart, syringe pressure from the caliper end. Pushed through as fast as possible. Piston bleed port port is uncovered. Work the pedal very small strokes.
I am careful to not overstroke the piston (Ishy or Ringo's tip about drawing air in the piston seals on return stroke.) I would try vacuum from the reservoir end, but I think they are right, I'd just pull more air into the piston seals.
I unbolted master cylinder, contorted it to get the inlets/outlets to the highest point. Tilted the caliper down to be the lowest.
Tapped, vibrated, and wiggled things more than a middle eastern dancer.
Still some air in there. There are brakes, but the lever bottoms on the frame before locking the wheel.
Any other ideas?
k
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ok, its not the genuine article, but this works for me.
Reminded me this weekend when changing fork oil: I use a plastic baby bottle to refill the forks. (when the springs/dampers are still connected at the bottom.)
The baby bottle holds 300 ml. Cut off part of the very end of the nipple. The remaining part flexes and goes in between the spring coils and gets the oil in easily.
Every other way I have used ends up with more on the outside than in the forks.
k
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for the future, Sprocket Specialties (or is it Specialists?) is in Califormia. They have about everything.
Not much difference in prices though, so I just mail order through the trials dealers and support them. k
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great to hear you got it, thats a miserable task.
To add, use Left hand drill bits for drilling a broken screw. Sometimes the LH bit will bring a broken screw out all by itself. especially 6 mm case bolts.
The common easy outs with long coarse flutes tend to wedge the screw outward really bad sometimes. Just sticking the screw in tighter.
I have a very old set, but I think snap on still sells, that has a fine LH spline and shallow taper. There is a square sholder at the top, instead of continuous taper. The drilled hole has to just right, but then the shoulder hits the broken bolt and it doesn't wedge outward so bad. They work great.
k
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almost an entire 305 listed separately as parts on ebay, US runing about another day.
k
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Great advice.
EVERY bolt that comes off, ever, on anything I own, gets never seez. Worth the effort in the long haul.
k
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ab:
Last time i checked with bob he didn't have any, that was year back. I need the little clevis also, that will be harder to find or adapt from something else.
One of my 'ty in a box' projects came without both parts, so I assume it had the clevis moved to the extender, then someone took it off before I got the stuff.
no rush, i'll ck with bob again later.
tks, kcj
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Does anybody (pref in the US) still make the clutch extenders for the gearbox end lever? I need one, plus the clevis that holds the cable end, to replace one I lost.
kcj
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can you elaborate on how this change was done? machined off the cases and slave cylinder installed, or was it a cylinder that just pullled on the original lever out of the case?
just some brainstorming for another 'someday project'. kcj
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the tool is really handy, and saves risking gear teeth or basket parts.
pic of a homemade one is attached.
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look for restricted flow of fuel, air in, or exhaust out
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I need to update pegs on some older stuff.
Do any mfrs sell the mounts ready to weld on? Speed& Sport had a weld on kit,but I don't think it used std. trials pegs.
anyhill: what do you ride that has bolt on brackets? perhaps I could adapt them.
k
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do they then become stronger than the brackets and cause the brackets to fail?
I am looking at better pegs for kids, but don't want to move the fuse link from the peg to the frame.
k
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I'll probably just confuse things worse but here goes.
SAE rating with a W is rated at a cold temp ( I think 0 F), oil without that is rated at (I think ) 104 F
All oil thins out when it heats up. That drop is called viscosity index. Whatever the base oil does is by definition VI=100. Oil that doesn't thin out as fast with heat has VI greater than 100. 120 to 160 is typical of multigrade oils. Some really good fluids, or ATF, have VI approaching 190 but thats rare.
An oil that tests out cold to 10W and has no particular VI improver additives would be a 'straight weight', technically a 10W-10 I suppose.
Oil that has VI improvers still thin down with heat, just not as fast as the straight grade.
So something that tests at 10W, but doesn't thin out as fast with heat may be thicker than base 10 oil at high temp, and would meet the 40 grade. It would then be a 10w-40.
The advantage is obvious: better flow at low temps, still good viscosity strength at high temp.
The down side is that VI improvers are not real stable. They tend to shear down with time. So the oil that started life as a 10W-40, after lots of time in the engine, may end up as a 10W-30, or 20, or 10W-10.
My conclusions:
1. Clutches shear the oil badly, so the VI additives may not last long.
2. How an oil works after 10 or 50 hours may not be how it works when you first put it in.
3. Oil and filters are cheap, change it often.
k
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