KLR 650 Modifications

Thanks. Damn, the bike has 1100 miles on it , really shouldn't be needing that repair yet.

You can also just remove the diaphragm block with gaskets and spring and the back cover and make a little aluminum plate and gasket and convert it to manual yourself.

It could be your gas tank cap's vent. Ride with the cap open and see if the problem does away. I'm not sure on a fix for that if it is causing the issue.

And instead of the petcock diaphragm leaking the vacuum line to it could be leaking or have a bad seal over the petcock...and just like a diaphragm leak, it could prevent the valve from fully opening.

Or some junk in the carb, of course. Also make sure your carb vent isn't restricted and while your at it that the fuel tank vent (under the seat) is also not restricted.

As most of us know, there's a list of issues that can potentially cause surging. The most common causes involve something that is leaking or pinched.

For anyone with an aftermarket exhaust-

Do they really do much? I have a big gun full exhaust the previous owner installed. He gave me the old exhaust, but the clamp that holds the muffler to the header is missing. I'm getting sick of hearing the big gun, but if its actually helping I'll leave it on.

I just figured I'd ask before I bought a clamp then went through the changing process. I hate to give up HP, but this thing is getting annoying.

All typos and misspellings blamed on my phone.

@jules083

I think the only real gain on a stock KLR is the weight savings.

The aftermarket exhaust might increase the HP if the PO re-jetted carefully. But I've bought enough bikes that were badly jetted that I'm starting to think that people don't think that much. If the PO did re-jet, you'll have to do it again to really test the stock muffler.

My KLR came with an obnoxious-loud aluminum muffler and a drilled and gutted stock muffler. I got an unmolested muffler from E-bay and the bike was easier to ride and far quieter. The bike came with stock jets so it didn't run very well with the aluminum exhaust.

I think someone was selling those already made up as a kit at one time. Probably a good thing to have along on a trip, or a drop in ready manual petcock like Eagle Mike sells for like 25 bucks. I think it's a Yammy TW200 petcock.

Make sure that the vacuum line at the carb is properly blocked off/sealed if this mod is done. I did this mod about 40K ago as well as the removal of the 'other' vacuum asisted polution stuff - then just the looped the hose between the 2 vacuum takeoff points on the carb.

i have gone back and forth between alumnium and stock pipes on both of my klrs a number of times. an aftermarket can like the big gun or lexx will give a slight increase in power if you re jet. it is defiantly noticeable to me in the mid-range. but im sure it is very slight maybe 1-2 hp? i choose the louder pipes because i like the fact that they tend to chase off the deer on the back trails i ride. and they do defiantly help with alerting Miami drivers.
i always run some type of quiet core and spark arrestor combo to take the edge off the roar and be forest service legal.
you can get a quiet core and spark arrestor for that big gun you have, then pack it with steel wool and it becomes a good pipe that weighs less than half the boat anchor the klr comes with. every bit of weight you remove makes a difference in performance....and the performance im talking about is the performance of my lower back when i pick the pig back up in the mud

It's the one with a spark arrestor, not sure if its a quiet core or not. After talking to the last kid (owner 2) I highly doubt it. Typical kid you would expect to see on a gsx-r or something.

I'll look around for a quiet core, see what I can find. It's not too bad as long as you're off the highway. Backroads its fine, just that constant drone is what kills me. I've even thought about trying to make the tip turn down somehow, maybe to divert some sound.

And I do need to do some jetting. I went according to dynojet's instructions and I think its too lean. Getting 38 mpg on the last tank, that can't be right.

All typos and misspellings blamed on my phone.

38 mpg sounds like its too rich,not lean,unless you are riding it hard.

I don't know what I was thinking when I typed that. Meant too lean.

I think the muffler change and subsequent rejetting helped mid range and slightly higher. I feel the jetting did as much as the exhaust. My mpg sucks but I spend much of my 35 mile commute at 5500 RPMS and higher. But 30 mpg on a motorcycle beats 13 mpg in a Durango.

You just did it again !

ghead: ghead: ghead:

All typos and misspellings blamed on my phone.

Edit- just noticed the banned thingie. From my phone it was a picture of a guy beating his head on a brick wall. :huh

Dynojet kit is far too rich. Their needle taper is good but main jets are way way too rich. Use their needle on 2nd clip then go with an OEM Keihin 142 main jet or if you want a bit more mileage go with a 140. Properly jetted the KLR will give you 46-50 mpg in mixed riding.

I made some progress today plumbing up the Fox reservoir.

So, I'm reading a recent Dirt Bike article on the KLR650. The author claims to have gained 7 hp (from 33 to 40) with an FMF pipe and JD jet kit. Seems that most others around here tend to disagree that such a large gain is possible.

Here's a dyno chart http://www.pbase.com/image/110004615

I'm confused

:huh

I hate to say it, but it does seem optimistic, unless the JD Jet kit is that good.I doubt it.
I've often wondered about the Jd kit on the Klr but no one seems to have done much testing.
The Ktm guys swear by the Jd kit though.
Which FMF muffler was used in the test ?

Have you seen Patmans big dyno writeup ? He could not get 40 and had alot more mods done.

q.v., "Fantasy Island," network TV series of the past (info on Google).

Relevant quote:

Tattoo: "De plane! De plane!"