XR440 kit

[Trailryder42]

I did some research and found that replacing the one between the ears is too expensive, so I just bought a compass.

 

[DualSportr]

I just bought a compass

Y'know, that's a thought!

 

[Trailryder42]

Was looking thru some old threads and found this and figured I should put some kind of closure to it since I'm the one that started it.

Well, it took 4 years, but I finally did the 440 kit from Thumper Racing. Taking into account everything I learned in this thread, I kept the stock cam and had Kibblewhite valves installed during a valve job. Also replaced the camchian for good measure. As discussed, temps did go up significantly, 30*-40*F oil temps that is, even with running the cooler DPR9Z plug. Wrapping the header tho, dropped temps back to pre- 440 levels.

Since doing the 440 kit a little over a month ago, I have installed the Mikuni pumper and I have to agree with XRs Only, this "is" the carb that "should have been" on the XR.

I also installed a Hebo hydraulic clutch to offset the difficult lever pull from the heavy duty clutch springs that were part of the 440 kit.

Now I'm considering an exhaust can. I don't want it loud, yet it should have better flow and performance than my Gordo modded stock can. Looking at the WB E Series and the FMF Q.

 

[Danman]

Holy resurected threads Batman! Just kiddin ya :) Glad its workin out for ya. My 350 has the Mikuni pumper on it and when I ride my buddies 400 it sure does not have the good throttle response at all. Glad your diggin the 440.

 

[TR]

Has anybody weighed the pistons in the 440 kit ? I would image one would pay the most for the lightest piston. Thumper Racing claim they have a super light piston made by Wiesco. Is this kit exclusive to them ? Which 440 kits has the lightest piston ? How can one make an objective choice ?

Any comments ?

I have an XR400 and am looking at a big bore kit ?

Thanks in advance
Tom

 

[Trailryder42]

Best thing to do would be to call Thumper Racing and talk to Russell Hicks. They are really friendly, helpfull.

 

[TR]

Cus, which kit did you buy ? What is the compression ratio of your kit ? My Xr400 runs the j&E 406 with HRC cam and CRD Absolute performance exhaust. I think with the HRC cam I can run the 12.5:1 to kit and use our good Australian fuel.
Thanks in advance.

 

[Jaybird]

Wrapping the header tho, dropped temps back to pre- 440 levels.

Wow...I love reading the old stuff over again. This place is a trove.

I am very interested in hearing anything you can offer about your header wrapping experience. What convinced you to do it, detailed results, etc...

 

[Trailryder42]

Here Jaybird.

http://www.4strokes.com/forums/topic.asp?TOPIC_ID=20127&SearchTerms=exhaust,wrap

http://www.4strokes.com/forums/topic.asp?TOPIC_ID=20364&SearchTerms=exhaust,wrap