Keihin 26mm, 140cc, jetting for larger exhaust??

[Divy]

my exhaust should be here tomorrow an wanted to know if i have to re-jet the carby
if i have to do i change the main jet? up a size or...

my carby is a mikuni 26mm its on a 140cc with a uni filter the new exhaust is a 32mm pipe an comes to a 40mm muffler

cheers guys

 

[motoluver]

my exhaust should be here tomorrow an wanted to know if i have to re-jet the carby
if i have to do i change the main jet? up a size or...

my carby is a mikuni 26mm its on a 140cc with a uni filter the new exhaust is a 32mm pipe an comes to a 40mm muffler

cheers guys

I believe i have the same header as you with a different muffler. There is defiantly a jetting issue as my friends stock DHZ 140 has more power then mine with a H-bomb exhaust. Last time i went to get a 105 main for my carb the bike shop did not have one I'm just going to take my current main jet to the bike shop and get them to order a 105 from Mikuni.

 

[Divy]

yeah it does have the same header as your H-Bomb, so you reckon if i play around with the main jet size it will help it ??

have you tryed to adjust the air/fuel screw an needle clip??

 

[motoluver]

Nope just going to do what everyone recommends and get a 105 main and then work on fine turning the carb.

 

[Fenton]

You may have to, my mate just bought a new exhaust for his thumpy, and atm it shoots flames and backfires very loudly.

 

[mr_sikma]

where do you get the exhausts from to suit?

are they all universal?

 

[pitbulls]

mate of mine bought a h-bomb copy exhaust of e-bay and now the bike runs like ****.Motorbike shop told him to check this out.sorry only format avail.

 

[Juls]

The biggest issue with exhaust systems is the price,

you can buy the cheapie ones or "knockoffs" for $100-200

but often they don't work, or make the bike run worse.

the real issue is, if you want a real pipe/header set, then your up for $500,

the other issue is they don't really make the pipes to go on these cheaper motors in our chinese pit bikes, most of the pipes are designed to use with a modified CRF50 motor or similar.

I guess something designed to work with a modified KLX110 would be the closest option.

Juls

 

[Divy]

well the exhaust came today i bolted her on an took it for a ride to see how it runs
it runs pretty good and has a tuff sound but the carby isnt adjusted, when i let go of the throttle it back fires no flames just popping but i reckon when the carby is tuned it will run good

i put new plastics an sticker kit on too an the exhaust is a lil too close to the side plastic an melted it abit lol

oh when i first got the 140, when i accelerate hard the engine revvs high as it should but it takes a second for the bike to move with the revvs if that makes sence to ya's whats going on??? cause its still doing it

p.s juls were dis you get your 102.5 main jet??

 

[motoluver]

i put new plastics an sticker kit on too an the exhaust is a lil too close to the side plastic an melted it abit lol

Happened to me to. If you dont fix it say goodbye to your plastic and sticker. I took one of them rubber blocks of my old exhaust and fitted it into the the spot on the plastic so now the side plastic sticks out further and doesnt touch the pipe. I can get a pic if you want.

 

[Divy]

thanks for the info motoluver, i did something a little different i just used this thing that was on my old exhaust,

i have 2 questions to ask
1. alot of people are puting bigger main jets in there carbys so there 140cc runs better but my carby is a 25mm mikuni will that be ok with a 102.5-105 main jet or will i need a 30mm carby an bigger main jet??

also when i first got the 140, when i accelerate hard the engine revvs high as it should but it takes a second for the bike to move with the revvs if that makes sence to ya's whats going on??? cause its still doing it

please help

 

[Meko]

Sounds like ya clutch is slipping Divy, should be very a direct feel with the engine revs - no delay

 

[jamie__1221]

yeh your clucth is sliping mi done the same thing i hadd to back mi cable of a bitt

 

[Divy]

it only does it in second, so if i back off on the clutch cable adjustment it will stop??

or could it be some thing else making the clutch slip??
thanks guys for the info
any one know about my carby question by any chance??

 

[jayde156]

i have a 140 with 25 mm carby and ive just tuned it and it runs fine....i dont think that you need a 30mm or 32 mm exhaust. i still have my 25mm exhust from when it was a 125, it does the job fine.

 

[jamie__1221]

yeh itss just your clutch cable well try the cable anyway and if it dont fix it its sumfin else
with the carby just ride for a bit and see what u think but u shouldnt have to go bigger maybe just a re jet to a 105

also with the new 140 head the exausht port seems lik it could do with summ porting just what i think