jetting for winter with fmf k&n

[germanblaster]

Hi

today my blaster got street legal and i will receive my fmf fatty exhaust system soon.
In this case i have to order some bigger mainjets for the stock mikuni carburetor.
My setup is:
-everything stock: bore, reeds, carb etc
- K&N Airfilter
-I have a stock airbox lid and one with some holes

My question to you experienced blaster experts is:
what range of mainjets i have to order
I considered to order mainjets from 250-3??
Is this the right size?
Hauptdüse HJ für Mikuni Vergaser Groeße 290 | eBay
Mainjet 230 & 240 i already own.

The current average temperature here is 0° Celcius (+32.0 °F)
My country is located 40m above the sealevel

I am looking forward to get some informations from you.
Thanks a lot.
greets

 

[Awk08]

heres straight from the manual, if your oil injection is still in operation, i'd follow this, or possibly bump the main one size just to be safe

 

[germanblaster]

thx
and what jets i have to order for k&n +fmf ?

 

[webmonstro]

thx
and what jets i have to order for k&n +fmf ?

I Have fmf and a uni air filter with no lid on
I like a 280 jet in the summer 290 in winter
I also recomment boyesen dual stage reeds and did a 4º timming advance
Nuno

 

[piezzi]

I'm at ~2,500 ft elevation and all stock except for FMF fatty, K&N, no airbox lid and I use a 300 main. I'd get jets ranged from 310 down to 250. Start with 270 with the stock pipe and airbox lid and start with the 310 for the FMF without airbox lid.

These are only starting points for jetting, and the only real way to know if you've got your main jet right is to do a plug chop.

Good luck!

 

[germanblaster]

my budget is to low to buy some new reeds /:
but the 4° timing is possible are there any descriptions of this modification available?
i think buying some jets from 260-to 300 will reach to get the carb setted ?!?

 

[Budget_Blaster]

The old ladys is sitting at 300 main stock jet needle in mid position with .050 wiseco,fmf gnarly,uni and no lid,boysen power reeds.

Our current temps are about 30-45F and it looks about perfect.

If it were me id order 260-310 and start at 310 and work your way down better rich and safe than lean and sorry.Its just my personal preference but i tend to jet on the richer side for a margin of safety.As long as its not pig rich the power you give up for peace of mind and longevity are more than worth it IMO.

And if for some reason you are running the injection scrap it asap!You dont need to buy a kit or anything just some 5min 2 part epoxy.

 

[Larry's Shee]

http://www.blasterforum.com/do-yourself-20/diy-4-degree-timing-advance-pics-2417/
There you go. When jetting, remember plugs are cheaper then pistons.

 

[xjma]

250 to 300 should give you what you need. With the FMF on there, throw the 280 in there and see how she goes from there.

reeds are like 20-30 bucks, get boyesen dual stage reeds, the increased throttle response is worth it!