XR650L Mod Questions

XR650L Mod Questions

I want to add some items to my bike. I want to let the engine be all it can be, but not at the expense of reliability and to some degree long term durability. I have a xr400, i am going dual sport here, not trail only. So here goes:

1. I need a larger tank, what I am seeing on the blogs is that the INS tank is hit and miss on quality and fit . So it is out. My local Dual sport boutique says that XR650L’s sometime have head overheating problems with some brands of tanks because of airflow changes. I read good things about the Clarke 4.7gal (will most likely buy this one). The Acerbis makes the larger and more expensive tank, and from the picks I have seen it appears that it has wings that (might) grab the air much like the stock tank shrouds. Any thoughts?

Link to Acerbis tank: http://www.chaparral-racing.com/Chaparral/productr.asp?pf%5Fid=257%2D1590%2D06&gift=False&HSLB=False&mscssid=718712D4625847B9B355EA9ECC7D3BC7

2. The sky is the limit on engine mods. I will spend some money but I don’t want to get crazy. So I am going to start with: De-smug mod. XRs Only Competition Exhaust, Stock header with exhaust insulation wrap. Mikuni 41mm flatslide Carburetor. Uni Air Filter. Stock cam and Piston. My question, is what gain will I see. Should I upgrade to the Keihin FCR 41mm Pumper, is it work it? Is a 10.5 :1 piston worth the trouble. Is durabilty and overheating an issue with the HC piston? Do cams change the torque curve looseing low end grunt. Is there a diminishing return.

3. Oil Coolers? I like the idea, but this seems real expensive. link https://secure.srcinc.net/prodpage.cfm?Cat_Selected=1&SubCat_Selected=14&Product_Selected=1661&StartRow=11

4. Extended Cylinder Head Fins - added cooling?

Also on the shopping list are springs for my weight and case guard, heated grips, better bars ect ….. Family will have no trouble finding gifts for me anymore.

You may have some trouble mateing that stock header to the XRs only tail, big diff in size of the pipe that is used. I am running a XRs only full system in stainless along with the mikuni flat slide from XRs only and the combo is working out fine. Alot of people here choose the edelbrock quick silver instead with good results. Good luck!

A cooling hint- people say the wings on the stock tank are bunk, but they're there because of that huge, floppy front fender, and getting stuck in 5mph commuter traffic.

A smaller fender, or trimming the stock one, will greatly aid cooling.

If $$ are no problem, and you're going for more dirt, how about a built-to-the-hilt XR600R engine?


just bought the 2001 xr650l, so that is the bike/engine i have to work with.

good tip on the fender, i will look into that. thanks.


If anyone's interested a fender from a XR400R is a direct bolt on, its higher in front (no droop) and shorter in the rear seems to allow better air flow.


What is the best way of getting a 400R front fender? Aftermarket!

I ordered an Acerbis 400R fender from Rocky Mountain MC.


I did "Dave's mods" (remove snorkel, uni air filter, rejet, aftermarket (disk) exhaust), exhaust wrap, remove smog, then remove wings, cut off 6" of the front fender and cuts holes in the tail end of the front fender improves air flow to oil and engine...........it's like a new bike. Runs at 220 degrees. Oh yea 14 tooth front, 47 rear sprockets, all day running top end of 65 mph, can push it higher but never have for any distance cause it's not a street racer, but it's great for trails and city commutes. I've owned a street bike, no choppers, and there is a difference, the 650L is not the best bike for trails or street but does work on both pretty well for my taste.

My humble opinion it's pleanty, wheel raising, fast without changing the cam, or pumper carb even though I've read those both are nice to have.

I also have the fork brace and it did make a difference, no damper though, just too much money for my taste.

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