YT60 Big bore jetting and tuning.

[HarrisoN*]

so im running a BBK that was fitted by previous owner, believed to be 80cc with standard head, pipe and carb on standard jetting with a uni air filter.

at the minute im still running the oil pump but im soon going to switch to premix, although it still takes off and pulls okay I think there is more power to be had out of it power wise as its still on a par with a stock bike in terms of acceleration and only a slight increase in top end.

Ive been through all of the mod threads but can't seem to find any advice on upjetting, I believe standard to be 92.5 and the carb the same as a pw50? so jets from that would work. Anyone running a BBK and got any advice on what to upjet too and what else to do?

im gunna take the exhaust off and clean it out and do the mods in terms of removing the restricting washers but while its apart I figured sort the fuelling aswell.

[HarrisoN*]

anyone?

stock is 92.5 on main and pw80s run 120-130. I know jetting is very much trial and error but a idea on others base settings would be good.

I see pw80 carbs on ebay with 19mm ID sleeves, and pw50s with them too so im guessing I could fit a 80 carb providing the yt manifold is 19mm OD?

http://www.ebay.co.uk/itm/Carburetor...item19eddf5b4c

http://www.ebay.co.uk/itm/Yamaha-PW5...65020492&rt=nc

[CRAZY70MAN]

We ran a 26mm carb on my 2 speed nos zinger at trikefest a few years back. We used rubber boot to connect it. Not sure of jet size but it did handle it with open air filter.

[3 Wheel Drive]

I've got the Molassi 70cc Big Bore Kit, high compression head, boyseen reeds, and a DG pipe.

The instructions on the pipe say it may require up to 2 larger jet sizes for the pipe. I tried at least 3 different size jets and went back to the stock jet. I found it worked best for me, running 110 octane. I've never seen an 80cc zinger or heard of BBK, post some pics.

The 70cc kits are a blast to ride, 80ccs would be even cooler! It seems like some machining would be required to the cases to make it work? I'm just running a stock carb.

[rayatc84]

My Zinger has the 70 Malossi kit + high compression head + DG pipe.
It has stock carb + jetting and reeds and run very well.

[1upfront]

you would benefit from a larger carb i run a mikuni vm20 on my pw80 swap atc70 and high compression head with 110 octane im up to a 210 main jet. id benefit from a bigger carb too probly could handle a 26mm.

[HarrisoN*]

The kit was fitted by the previous owner it was 80, It maybe a 70, hell it may even be 60 AHA! but im not keen on pulling the head just to measure as its mechanically great just fuelling is out. Ive found jets on ebay so im gunna order some up and try 82.5 just to see if it fuel starvatiob and then a 102.5, I can always drill the 102.5 upto a 112.5 if I find it still not enough, then if it does pull better with the 102.5 or 112.5 Il go upto the pw80 carb and adjust the jetting in that. I run 95 octane purely because here in the UK fuel prices are stupidly high and the extra for 110 isnt worth it.

I keep meaning to pull the carb and plug and see how they are but so far all I seem to have done is begin making wider pegs. but toying with the idea of making a more free flowing pipe too.