Would I have to jet with this slip on?

[represent618]

I have a stock powertrain 07 450r

I am considering adding the motoworks slip on, does anyone know if I would have to jet to run this, or can I slip on and run?

http://www.magicracing.com/Motoworks-SR4-Slip-On-Exhaust-System-Honda-TRX450R-06-07_p_230-3608.html

[stoopidbot]

Everyone will tell you yes you have to. I have an 07 450 also, I put a 2 brothers slip-on on mine. I did not rejet for it. It runs perfectly fine, back fires a little but nothing unhealthy. Put the pipe on and start the quad. You will know instantly if you need to rejet.

the 450r exhausts are very lean from the factory. they actually almost need rejetted right away, a lean motor will seem to run well, but the lack of fuel can cause many problems.

anytime you change the intake or exhaust, you should do plug chops to see if your jetting is on or off. lean is very bad and by increasing air flow in or out, you are making the mixture lean.

[REPOMAN]

exactly. there is a reason the ENGINEERS say to rejet. the reason is because they know what they are talking about. i rejetted mine and you not only notice a power difference getting right amount of fuel but mine will surely outlast the people who say there quad runs fine with the stock main jet.

[represent618]

Can you tell me what jet sizes you used?
Did you do a complete exhaust or a slip on only?

I appreciate your help.



Originally posted by REPOMAN
exactly. there is a reason the ENGINEERS say to rejet. the reason is because they know what they are talking about. i rejetted mine and you not only notice a power difference getting right amount of fuel but mine will surely outlast the people who say there quad runs fine with the stock main jet.

[stoopidbot]

I have changed my main jet to run at the altitude I live in but that's it. It has been rode every weekend since July of 07. No problems, And Honda Mechanics are the ones who told me I don't NEED to rejet. I would listen to them before any of you.

[REPOMAN]

i have a 180 main with full fmf exhaust k&n filter and half an airbox lid. stock in mine was a 118 main. i would ask them when ordering what main they recommend.

[represent618]

In your opinion, was the increase worth the investment?

[8my_Cash]

if you doing a slip on with stock air filter with the lid off just throw a 165 main in there and start from there.


THis is what i did with a plug chop and its perfect, this is due to just letting it breathe a little better but nothing major.

If you run an aftermarket filter you might want to change your slow and leak jets as well.


165 main is a good start, with a full system a 175 is a good start as well.

i have the same year bike as you.....just remember 04-05 are way different than the 06+ years. Different style of carbs.

Originally posted by stoopidbot
I have changed my main jet to run at the altitude I live in but that's it. It has been rode every weekend since July of 07. No problems, And Honda Mechanics are the ones who told me I don't NEED to rejet. I would listen to them before any of you.

go ahead and ask your honda mechanic...i'll give you an idea of how good the honda mechanics are...

i put a tokyo mods carb spring in my 06...when i did that, the plate on the slide fell off and i put it in upside down. the next day, i loaded the bike on the trailer and took it to the shop for the starter recall. over a week later, when they were only supposed to have it overnight, and many phone calls as to what the holdup was, and them telling me it wouldn't start or run right. finally i was told it would be ready the next day. i decided to go pick up the bike since i was going to near there anyway. i had told them about the spring, that plate coming off, etc. i went and pick up the bike with it being torn apart...still not running. i took 10 minutes to fix it.

look at it this way...honda has a schoo...it graduates people just like your high school...were all of them a+ students? did they all get 100% on everything?l

[represent618]

thanks for the input guys.

Honda Mechanics are no different than any other profession, some are better than others, some are less qualified to do the work than you doing it yourself.

I have a local Honda Shop with a couple of the best rated mechanics, right next to them in the bay are a couple guys that I would not let change oil in my lawnmower.

[stoopidbot]

Originally posted by represent618
thanks for the input guys.

Honda Mechanics are no different than any other profession, some are better than others, some are less qualified to do the work than you doing it yourself.

I have a local Honda Shop with a couple of the best rated mechanics, right next to them in the bay are a couple guys that I would not let change oil in my lawnmower.

Exactly, I wouldn't let just anyone touch my stuff. I have been using the same mechanic my whole life. He started out as my dad's mechanic in his racing days. He kept my dads bike running at peak performance for many Baja 1000s. I trust his word more than anyone else.

you can trust him all you want, but he is wrong...of course...you said you changed the main jet for your elevation..there for YOU REJETTED. it may have been rich enough to use the slip on without rejetting for a 2nd time...so you may be confused in the way he handled your addition of an exhaust...

[stoopidbot]

The elevation jetting was a must. I ride in Colorado around 10,000 ft most of the time. When I think rejetting I think of the needle setting and all that other stuff. Like a jet kit, not just the main. So, I stand corrected.

[warr72]

165 main 52 pilot 60 leakjet or put adjustable leak which I went to from R&D. Put an aftermarket filter in and cut rear portion of airbox lid. Then your slip-on and you will not believe the difference. :eek2: If you want more add a stage one or hrc cam and hrc header to same set up. Uncork the beast and it will haul.