Just purchased an HMF ( polished )...questions for the HMF owners

[srx2002]

Anyone purchase this system and leave the Carb setting stock? I really don't wanna be messing with the inside of the carbs.

I have a T-boost, K&N Filter, and I ride with the t-boost on 90 % of the time . My stock jet sizes are 152.5 for 2,4 and 155 for 1,3. and I'm at Sea-level.

so....whaddya think??

Brian

 

[one2dmax]

You should be able to bolt it on and go. Carbs could benefit from having all the jets the same size and could probably even go one size leaner.

Sean Morley

 

[srx2002]

Really?? I always thought from what I read that jetting is a must....and I would have to richen the mixture when putting an aftermarket header?

Or is the T-boost on often, K&N filter, and the fact that I'm at sea level have alot to do with not needing carb rejetting?

 

[maleko89]

The 85's and some of the 86's had bigger mains for the rear cylinders because those cylinders get pretty hot. See how it pulls from 7500 rpms to redline. If it's worse than stock, then lower the main jets to Mikuni 150's.

Most of the time, needle and mains are fine stock when going to a full exhaust and stock air box. The tricky part is getting the low end to perform like a stock bike.

Mark
#1098

 

[srx2002]

so are you saying that my 06 with the new HMF is NOT gonna perform as well as my current stock setup in the low to mid?

To be honest I live in a pretty small place and most of my riding is done in that range.

 

[maleko89]

You'll notice most of the difference in midrange and top end....that will improve because of better flow. It's just that the stock exhaust was specifically built for the low and midrange.

In my case, I just adjusted the mixtures screws a tad. I have stock pilot jetting except for PAJ2....that's a 177.5. I can give the bike WOT in 5th gear and it'll pull from 1500 rpms.

If you find a rich or lean problem at off-idle below 3500 rpms just increase PAJ2 for rich problem and decrease it if it's lean.

Mark
#1098

 

[srx2002]

OK...so putting the HMF exhaust will not DEGRADE performance over the stock exhaust in the low, mid and high rpm range given that I don't want to make any changes to the carbs at all.

All I have is a t-boost, K & N filter, and runnin at sea level. ( COMPLETLY stock carb settings )


P.S a yes/no answer will do just fine ...LOL

 

[maleko89]

Maybe...depends on current tune of bike.

Mark
#1098

 

[srx2002]

ok...depends on the " current tune of the bike " well all I can say is that it only has 6400 km's ( 2006 model ) It has a T-boost and a K & N filter with the drilled exhaust mod. I keep the carb's sync'd regularily and the vmax in it's current state can pull from 5th gear from 1500 RPM with no hesitation, and no stumble. ( she doesnt take off fast mine you.....but seems pretty smooth to me.

On that note...My friend has an 85 with a dyno stage 1 kit. I can pull away and leave behind at any speed, any rpm, any gear. I drive his one and it seems like a turtle compared to my 06. I can pull wheelies on mine...I can't hardley get the wheel off the ground on his. I can simply drive along in first gear....give her a shot of gas and the front comes off the groung pretty easy....I cant do that on his one ( same suspension, same tire )

If that's any indication of how's it's running...??? I dunno.

 

[srx2002]

Hey mark, I have a better idea...I'll just put the HMF on and see how it runs...I'll explain the best way I can about how it's running..and maybee you can help me out then.

I'm just a little nervous that I might be getting in over my head with this jetting stuff...


I'm a little brain dead in that dept! :ummm:

 

[maleko89]

lol, I agree! Put the exhaust on and we'll go from there.

Mark
#1098

 

[shawn kloker]

Put the new exhaust on.It will be fine with the stock jetting.Make sure that you retighten the header bolts a few times after it warms up they will loosen.
Don't forget to change your underwear after listening to it the first time!

 

[veebooster]

I have an HMF system with carbon fibre cans. Carbs are stock. Runs great. No issues what so ever. If I decide to mod the carbs I'll go with Morley's jet kit.

Dale