Carb Switch-will there be an impact

[glozito]

Hello All,

I recently rebuilt my lower end and took out the oil injection. The top end was bored 020. I have a spare Mikuni carb 36mm, it fits the boot and the reeds. I have it connected to a twist throttle and the travel of the flat side seems adequate.

I swapped the main jet from the original carb but I just want to make sure that it wont run too lean or cause another issue.

My only concern about using this is that it came off of an RM85 and since i'm not a carb expert, it just seems like there might be some side effects.

I still have the original carb, but it had been performing poorly even after a rebuild prior to the engine pull.

Any thoughts?

 

[Awk08]

i doubt an rm85 came with a 36mm carb?,
and also that 36mm fits into our stock intake boot, it does not.

and you cannot just switch jets from one size carb to the next and hope it works, it will not

return the stock carb into the bike and learn to clean/jet it properly (search on here)

 

[Blaaster]

If the motor is stock, you will gain little or no benefit of the larger carby.

Post your mods for someone to comment on jetting and then to confirm that it is right do a plug chop.

 

[blasterdemon7]

If you want to upgrade your carb for a stock motor, a 28mm will give you a little better top end. You have to use a high flow air filter,good pipe and porting to benefit from a larger carb.

 

[glozito]

Ok guys and gals, my mistake.

The non-stock mikuni carb from the RM85 has a 00RP label and is stamped 03B 00 and HD X1 stamped on the intake side. The intake side measures ~27mm. I couldn't read the jet size from the RM carb, so i have no idea what it is.

For the time being I have removed the tors, put the stock carb on with a 240 main. (oil intake plugged with silicone) and hooked up the twist throttle

I know the RM carb was running smoother and was still hoping to use the flat side instead of the modded blasty carb. If it doesn't make sense, I'm okay with it.

Was just looking for an opinion before i fire it up and cause any damage. I put in a wiesco crank and a high compression piston.

One addendum: I did add the pilot mod as well.

Thanks for any further opinions

 

[blasterdemon7]

You can use the RM carb but you will have to jet it correctly for your motor. It will have to be jetted different from the Blaster carb. You can get a TORS delete throttle cable and use the RM carb and the Blaster thumb throttle. The RM carb is a 28mm.

 

[glozito]

So this is where I have no idea how to jet that RM carb.

Do I go lower or higher on the main?


Thanks for your patience with my questions

PS: My daughter wanted a twist throttle.... This quad is for her.

 

[blasterdemon7]

I'm not good at determining what's the best jet to use so someone else can give that advice. I do know it's safer to start with a to big of a jet and work down to the correct one by doing plug chops.

 

[brandoz28]

Twist throttle on a quad is not fun. Its a lot different than on a bike.


The inside diameter of carb on the Reed size is the size of the carb. I would go up a couple sizes from stock jet in that carb if you're planning on keeping it

 

[Awk08]

more than likely the 28mm from the rm is a keihin carb ??
heres some search results, read down thru them all to get a baseline for jetting, then plug chop to confirm (search for "plug chop" to learn)............

http://www.blasterforum.com/searchresults.php?cx=partner-pub-9438014176008015%3A9127094460&cof=FORID%3A9&q=28mm+carb+jetting&sa=Go