Li185 carb and gears question

[stoneislandv8]

I've had the engine upgraded on my Spanish Li125, casings split,all new seals and bearings, new cork clutch plates, gearbox reshimmed, GP race crank, GP flywheel, and Casa 185 kit. Kept the decent original gearbox but changed to 17T front sprocket and 81 link chain (should give 4.9 final drive IIRC)

Done circa 300 miles and got a couple of questions.

It pulls like an absolute train in 1st,2nd and 3rd but doesnt seem to have the pull in 4th. Can get to 50-55 (GPS'd) in 3rd but then struggles much above 55 in 4th. Its still running on 20mm carb which I know the kit should work well with but its also using the standard airbox in the toolbox.

Could the airbox and carb be causing a restriction in 4th? I wondered if I wasnt getting enough fuel/air through in 4th to get into the revs. Would changing to a 26mm carb with remote filter be worth a try?

Also, very occasionally it has jumped out of 4th but if you put it back into gear it won't do it again. The guys who did the engine work have had it back and couldnt get it to jump out of gear though so I thought maybe it was me not putting it into gear properly.

Did a run up some hills yesterday and noticed, WOT and hills in 4th it'll jump out....3 bloody times on 1 hill.

It's going back for a retorque next week so wondered if anyone had any suggestions....if the carb was worth a try I could get that sorted while its in....and if theres anything simple I could check about the jumping 4th issue before it goes back?

Ta, John

PS I put a new AF Clubman exhaust on it 6 months ago

[WINTERMODEL150]

I'm not to clued up with those spanish boxes but it sounds like a gearing problem to me rather than carb issues,personally i would run an italian li150 gearbox with 16/46 sprockets with a stretched 80 link chain.

Hope this helps

Dean

[starreem]

I run a Casa 185 kit with a KBA (clubman clone), PHBL24 and no airbox, just a unifilter pod on the end of a GP bellows. Pulls like a freight train and runs cool as a cucumber at WOT all day long. Running SX150 gear box with 18/47 sprockets, 4.8 final drive.

[Supereibar]

Hello John, I agree with the boys concerning gearing, it seems like different gears would help the engine to produce more speed on high revs.
On what concerns to the jump out of gear, I had that problem many years ago with a Jet200. She would always jumped from 4rth to 3rd. My suspicion was always a problem in the gearcog but I never checked. Years later I had the very same problem from 1rst to neutral. Switched the gearcog and that solved my issues.

I hope I was of any help.

Best regards,

Jaime

[stoneislandv8]

Thanks everyone, Jaime..great advice as always. Am off to see the engine builder tonight so see if they've got any suggestions...gears might be the logical route.Will let you know.

[stoneislandv8]

Gears seem to be the unanimous decision.....is it worth dropping the cog to 16/46 and stretched 80 chain on standard existing box or replacing complete with Italian Li150 15/46?

[SKP]

I've been running a SR185 for a while now using an italian li150 box and standard 15/46, tried using a 16/46 but scoot died on hills or into a headwind.

SKP

[stoneislandv8]

Finally, an update.....lost the airhose to filter in toolbox and added Ramair filter on bellows and changed the 17T front sprocket to a 16T and it goes like stink now, will pull 4th much much better. No idea on speeds yet as traffic was mental on drive home but it was def pulling past the magic 55 barrier it did have.

Adjusted the gear cables and its stopped jumping out of 4th.

Thanks everyone, happy days.

PS am still going to upsize the carb in next couple of weeks