Trail Bikes 108 kit - do I need a larger carb?

filthyboatguy · Jun 5, 2008

firepower354 said:
You get carbs on the "F" yet?

NO.

I need to POR-15 the inside of the tank and am waiting for the time and a nice sunny hot day to do so.

I have a tail and front fender going out for paint, stripe and clearcoat next month (current tail is a 1982 stripe, the bikes a 1981).

I GOTTA get some black grips on there, got them in a box also.

Kerker canister is getting Jet-Hot coated matte black later this summer.

Got some rotors going out for drilling and refinishing later also.

Need some high density foam for my big butt.

Carbs are cleaned, jetted and ready to go just need to treat that tank, it has very minor surface rust.

I want to have it on the road by October, with work, kids sports, and pimpin' the minis it's hard to find the time!

Soupamoto · Jun 5, 2008

filthyboatguy said:
Trailbikes

Honda Z50 parts CT70 parts XR50 parts CRF50 parts performance NOS Honda XR50 Z50 Honda minitrail CT70 Honda NOS parts Z50 CT70, Honda trail 50 70 , Honda Z50 CRF50 QA50 XR50 CT70 SL70 XL70 XR75 SL90 ST90 SL100 SL125 SL350 parts

Ahhh, Yes. That makes sense... hehe

Here was my LC4 Supermoto when I had it:

.

50rider340 · Jun 5, 2008

hey filthyboatguy, I just got some POR-15 to paint a CJ-5 frame is the stuff really good???? Its expensive. Sorry to thread jack this.

RAZZO · Jun 5, 2008

filthyboatguy said:
I miss the KTM, big mistake selling it. Got this to play around with now!

Wow!! Beautiful CB!!! They were and are still excellent bikes!

Soupamoto · Jun 7, 2008

Update:

Verified with the previous owner and the builder of the engine how the bike came to be. It was originally an 88 with the 20mm carb. They then upgraded to the 108 stroker and the owner said the 20mm came with the 108 kit so he didn't bother buying a new carb. He said TB then increased the size of the carb.

Whether the 20mm ever came with the 108 kit or not I wouldn't know; have only been into pit bikes for a couple weeks now. Either way, that is how the 108 & 20mm carb combo came to be. Funny thing is they both said the bike didn't bog with the 108 when they first built it. They didn't have any record or good memory of what jetting the used. Seeing how ya'll told me this combo is stock for that carb I suspect they did not change it at all.

I did make a mistake on my symtoms; the bike does bog up to almost half throttle. I tested better this morning. It mostly depends on how quickly the throttle is opened. If you open the throttle pretty slowly it doesn't really bog.

I have cleaned the carb a second time as suggested above. Pilot circuit is (and I believe was) squeaky clean. No change.

I dropped the clip from the middle to 4th down with little to no change.

Then dropped the clip all the way down. This made a noticable improvement on the bog. But, it destroyed the midrange! The bike stumbles and gurgles a lot at mid RPM/throttle. Not cool.

I don't have ready access to jets for this carb, so I've done all I can for now with the 20mm. I do have a jet kit coming as part of the TB maintenance kit.

I did buy the 24mm / 22mm (whatever you want to call it) TB carb that was suggested above. Got his maintenance kit too. So I'll test that next week maybe.

I got a Mikuni 22mm from So-Cal Motorsports (SSR Dealer); it came this morning (fast shipping!). So-Cal's recommended jetting on this carb is main 95, 51 pilot, 4th clip position down.

Side Note: The outlet of the 22mm Mikuni he sent me doesn't measure 22mm inside; it measures a hair under 26mm... think he sent me a 26mm by mistake? The numbers printed on the side of the bowl are 22 38419 23662. No clue if that is a model number or just manufacturing info.

I'll be putting this carb in next...

Soupamoto · Jun 7, 2008

Well, this carb didn't work much better. Worked perfectly for about 2 minutes until the bike warmed up, then the midrange gurgled. Got worse as I raised the clip. I ended up with the clip in the lowest position, but even that gurgles in the midrange.

I start a slow wheelie at low RPM, the front lifts, then as I need a bit more torque to hold the wheelie the bike stutters (girgles) and power drops off.

All I adjusted was the clip position. I'm confused now. Stopping for the day.

Thoughts?

firepower354 · Jun 7, 2008

50rider340 said:
hey filthyboatguy, I just got some POR-15 to paint a CJ-5 frame is the stuff really good???? Its expensive. Sorry to thread jack this.

We use it on our fendered street rod frames and suspension components. The stuff is incredible! Harder than woodpecker lips.

realgraverobber · Jun 8, 2008

Call TB and ask. They should be familiar with what you need for the setup.

Soupamoto · Jun 20, 2008

Psychoholic said:
ANYWAYS.... This guy is selling the shengway carb that came with the older 108's hes got it listed as a 22mm (probably because the number 22 is stamped on the cap) but im pretty sure thats the 24mm carb... Shengway's arent the best but 20 aint bad for a carb.

http://www.planetminis.com/f11/misc-crf50-parts-sale-85933.html#post895004

Same carb as I got on mine, works good for me!

So what jetting are you running with that carb?

Trail Bikes 108 kit - do I need a larger carb?

filthyboatguy

Soupamoto

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