stock 650L

The 650L is running great, stock. Starts great, great throttle response, no stumbling or surging, seems like a lot of power to me... Thinking I might leave it alone, even the smog turbocharger, at least for a year. I can not remember ever reading about a 650L on the internet, that had been left stock. Does anybody know of this ever happening before?

I'm sure there are a number of them out there. Some folks recently wrote topics on their mods and seemed very happy with them. If your 650L is doing what you want keep it stock for awhile. You can always add them as you feel you need them in the future.

Mine has the smog equip removed, Supertrapp exhaust and a carb that needs some adjustments to match the exhaust! It stumbles when getting on it hard. I bought the bike used and need to pull the carb and see what jets are installed. I like the bike for what it does and an afternoon of adjustments will cure it.

Enjoy your new bike!


[ June 01, 2002: Message edited by: Thumpster ]

Does your bike have the common popping and backfiring on deceleration? I bought a new '02 last Halloween, and I thought it ran pretty good, but I couldn't stand the backfiring. Removing the smog pump got rid of most of it, but then I ended up re-jetting, uni-filter etc. Once you start, it's kind of addicting. But if your satisfied with it stock, no reason to change.

Yeah, it pops on decel, it is pretty quiet really, more of a "puffing" sound. I hardly notice it really, I used to run a Sportster with drag pipes... now that's what I call backfiring!!! :)

Hey guys, I've got a question for you. I have a 02 XR650L with around 400 miles on it. I don't want to do any mods until after my 600 mile service. But I would really like to get the smog pump off of the bike now. I dont like the popping and puffing that it causes. I also had a situation yesterday where I was going up a pretty good size hill and kinda goosing the throttle on the way up and just about at the crest of the hill I heard a big pop and the bike almost stalled out. Thank god it didn't, cause it would not have been a fun trip back down. I've also had this happen when just coming to a stop and it actually did stall out. My question is, can this be removed for now without making any other mods? Has anyone done just this alone? Is there a performance increase, decrease or does it remain the same? I really appreciate any help guys, Thanks


As a disclaimer I purchased my bike with all the smog gear removed. After reading your post I scurried out to the garage and pulled down a box of extras that came with my bike.

It looks like a fairly straight forward procedure. There is 2 block off plates installed on the front side of the cylinder where the smog equipment routes to. The vapor cannister was removed and the hoses rerouted. Just removing your smog equipment should help your bikes performance.

I don't know the name of the manufacturer for the block off plates. I'm sure someone will respond with an answer and more detailed info.

Looking at my stock pipe (Supertrapp installed) I can see why people like to uncork them! Sorry, I'm sounding like a real rocket scientist here, hope this helps.

Is there a warranty issue for modifying your bike?

Good luck

Thumpster, Thanks for the info. I’ve heard that the XR650L runs real lean right from the factory and I would think that the smog pump would make it run even leaner, which I guess would explain all of the popping that they make when the pump is still on there. I’m just concerned that by taking it off without increasing the intake and exhaust flow just yet may richen it up too much. I know that Baja Designs sells these kits for around 20.00 and I would really like to get a nice cheap performance upgrade before the big uncorking. Thanks again.

The Baja Designs block off kit is made by IMS, Mine is sitting in a bag on the work bench waiting for the odo to click over 600miles (596 when I got to work this morning)

the kit was around $20 and it looks pretty straight forward, there are some vacume hoses and vent hoses that need to be "rerouted" so the bike doesn't huff and chug on acceleration

I'll probably install the kit in the next week or so and I should know then wether it gets rid of the popping on deceleration.


voodooridr, If the smog pump is the only mod. that you are doing please add your results to this post I'd really like to hear how it works out for you. Thanks

And thanks for all of the quick responses, you TT guys don't waste any time.

My educated guess would be that pulling the smog pump would either make it leaner or have no effect. I think it might be leaner because the pump draws filtered air from the airbox, removing it would seem to make more air available to the carb, thus a leaner mixture. It might be such a small amount that there would be no effect.

The air pump pumps air into the exhaust tract so it shouldn't actually lean out the fuel mixture, but the vacume lines on the carb do need to be rerouted.

Just wanted to let you know what I'm running. I've got a '93 XR650L with a Thumper Racing 675 kit, lightened flywheel, EAR supertrapp, IMS 4.0 tank, K&N Filter, no smog pump, XR's only skidplate, Renthal bars, Scott's chain guide, and a few more items. I installed a 41mm FS Mic carb. when it was still 650cc's. I remember taking off the octopus and the bike seemed to run better, but was still a little lean in the mornings. I installed the 41FS carb and gained a noticeable amount of response down low, not to mention it got rid of the lean condition. I did lose some on top, or so it seems, doesn't matter to me, I never rev it much anyway. Now that it is 675cc's I have left the 41FS on it and am thinking of going to a pumper carb. since I have had great success with a pumper on my old XR440. Anyone know of a pumper for the XR650L, or if the XR650R carb can be easily adapted to the L? I know Edlebrock doesn't make one for the L, they say there's not enough demand. Any ideas? Thanks!

My very first (and best) mod was to remove the smog pump. The IMS kit can be bought for about 20 bucks from either Baja Designs, or IMS's own website. It made no difference in performance. It did get rid of a lot of the popping. Particularly that loud pop you get when you shift from first to 2nd. You don't re-route any carb lines, but you do cap off the middle tee fitting that the small hose from the air pump went to. The only re-routing is the crankcase vent hose, from the top of the airbox to the bottom. You use a length of hose from the smog pump to re-route the crankcase vent. The whole procedure is about 20 minutes. All you need is a metric allen wrench for the bolts that hold the air tubes into the exhaust ports.

Well it's not the only mods I've made, so far the list goes like this;

IMS 4.0gal tank

Renthal XR400 bend bars (wider/flater)

Acerbis ralley pro hand gaurds

MSR DCL-X grips

XR400 front fender (stock looked too droopy)

XR600 Works Connection frame gaurds

XR's only large rear fender bag

Baja Designs shift lever

Next on the list is a Big Gun exhaust system and the Baja Designs jet kit with a Uni filter.

Hey Mike...85361's right on! I pulled my smog-stuff off with the IMS block-off kit and rode the bike for a few days before fully uncorking. I did notice a small improvement in the engines overall performance, especially low end. Also taking the smog gear off gives you much better motor access for later mods.. It took me about an hour for the job...I've posted stuff in the last 45 days with some good tips. For $20, it's your first move towards uncorking.

Thanks guys for all of the info. I don't know what I'd do without this message board. It's always nice get advice from people that have been through it already. The smog block-off kit is on it's way! Jim check your messages. Later guys, Mike

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