Upgrade piston, camshaft and carburator for XR650L

Guys,

I would like to increase torque and power on my Xr650L (already got airfilter+jetting, headers and muffler FMF, upgraded sprockets). I have been advised to replace my camshaft with an aftermarket one as it should increase performance. Apparently this modification is well established for the 600R and the aftermarket camshaft is the same.
Does anyone have any experience about it?

Moreover I have been advice to upgrade the carburetor as the original one is "depression" type and could be better.

Finally I have seen that there is a huge amount of aftermarket piston for this bike varying from 100 to 103mm. Any comment about these? Is it whorthet to install it? will the bike be reliable?

Many thanks&ciao

Nic

Yes,the bike will be reliable if you upgrade to a larger piston, me I like the 105mm 710cc and 106mm 724cc kit for the tq. and power it delivers.
I think this is by far the best mod for the money.
But any high compression piston will give you a boost in performance weather it be 100mm or 108mm just not as much with the smaller forging.

For the cam I would get a mild one or use the OEM cam for reliability, it actually works quite well as long as the compression is kept between 8.3.1 and 9.5.1. If you go to a 10.5.1 piston than you need to bleed off more cylinder pressure or use a higher octane fuel.
High lift cams with lots of duration and steep ramp angles tend to wear the valve train out sooner but how much on a XRL650 is yet to be determined mileage wise. Not to many people run a steep cam on the street but me hehe. The cam is the last thing I would do because it can transfer your power band to another location and it may not be what you're looking for.
Need more info on what you're trying to do.

For the carb you can use one from an XR650R that works very well and is on the cheap, 50 to 100 dollars for that mod, jetting is 65s pilot b53e or b53f needle two clips down or a b53d all the way down and a 165 main jet or more on the main if you have many mod's done to your motor.

Pumper carbs are the hot ticket for the 650L but they're pricey, 400 to 500 dollars but well worth it in my book,another one of the better mod's for the money. You can look for a used one but there hard to find.

Exhaust, they all seem to work well on the L because the OEM one is so restrictive.

Head porting, you really only need this if you want every last bit of power out of your motor, it does make a difference on the dyno.
Stainless valves with a 3 angle cut 60/45/30 is the way to go to finish off the head work.

The first thing I would do is add an exhaust and pumper carb or a XR650R carb if your lacking on funds and see if that will satisfy your needs and go from there, I see you already have an exhaust.
The pumper carb transforms the L into another bike coming from the stock CV carb.

Add all the mod's together and you have one very mean L.......

Many thanks,

this is very interestings and helpful.

Ciao

Nic

What cyclewizard said.........but consider changing the 2nd gear to the NX650 second gear,,it closes the 1st-2nd gear gap.........makes it a lot better in the woods.......and even in the city it is really nice.The gap moves to 2nd-3rd but since you are moving at a decent speed it`s not noticeable..

B

Thanks Brian for bringing that to his attention, makes for better wheelies.

Guys

I usually ride my bike into the Sahara desert where I hardly use the 1st gear...I also start with the 2nd. To make the bike "shorther" I replaced my front sproket with one with one theet less and increased the rear by three.

I do have an old NX650 park in the garage but I don't feel I want to cannibalize her...yet!

Ciao

Nic

Riding in the desert may tax a modified XR650L's cooling ability. I'd suggest a "big fin" head (cooling fins are welded up so that they are much longer) and oil cooler (the XR400R cooler is probably the most durable).

It's hard to beat the XR400 cooler for it's strength and durability.
And they're cheap compared to some of the other coolers on the market.
And for the big fin head, it's a must have for extreme hot weather riding.
100 bucks for the cooler and 300 bucks for a big fin head.

are you excluding the JAGG cooler from your comparison. I ask because of GSMark's Oil Cooler build. http://www.advrider.com/forums/showthread.php?t=500646

GSMark's cooler looks great....

Hi Cyclewizard,

thanks for all your explanations.

First of all the option of a better camshaft was suggested by my trusted mechanic. He is the most expert in XR in Rome...but beeing european he is not so familiar with the XRL model. I guess he was making his calculations on the XR600R compressio which I guess is 10.5:1 if not higher.

To summarize my bike has already a full exhaust FMF system, jetting, airfilter, wider airbox air conduit and 48 rear and 13 front sprokets.

So, starting from here, if you would suggest some mods what would you do:
1) 101mmm 10.5:1 piston?
2) XR650R carb?
3)Camshaft?

How much more in terms of power would these mods add?
Which piston would you go for?
Any idea of pricess?

Pardon my English...

Ciao

Nic

Put a FCR pumper carb on it,,,,,,and do the NX650 2nd gear mod........

Let`s face it,if you put a high compression piston in and a cam you are not going to gain much in horsepower..you might gain 5 or so....unless you go completely crazy with 105mm,porting,cam,carb.......

A good pumper carb will wake the bike up the most,without killing the engine life...

You can get more power from the engine,but you are going to spend a ton of money, and engine life can suffer,the main problem with trying to get alot of power from these engines is they are air cooled.....high power means high heat.......and the XRL can`t get rid of more heat than a little over stock........

Everyone wants these bikes to run like a new Husky or CRF or something but still be reliable,,it`s not gonna happen..........and the newer bikes have something like 12-1 compression or more.........and being water cooled they can take that for awhile longer........

If you want a fast bike,buy a fast bike.......these bikes can be fun,and have decent power ....but they definately have their limits..

If you put a 10.5-1 piston in it,you better be aware that it can spark knock/detonate badly.....


I`m sure CW can tell you what kind of money it`ll cost to get any real power increase........and the possible problems that can come from it too........he`s been at this longer than i...follow his suggestions on pistons and carb jetting and get a real good machine shop to do the work...




B

Hi brian, are you having problems with your HC piston spark knocking?
How about power, did it help you there or couldn't you tell the difference?
Have you thought about putting the stock one back in?

DR LC8, BTW: http://www.advrider.com/forums/showthread.php?t=114834.

all of your questions should be just about answered. "This in addition to your normal class load should turn your brain to tapioca in no time."

...so all in all...

Better carburettor (xr650r can do the job), nx 2nd gear and I'll get the most out of it?
I might go with it.
Is there any chance to increase the compression by lowering the head?

Your help guys is first class

Nic

P.S. All I would like is to get as much as an XR600r...

No.....i put in a XR600R JE 10.5-1 piston........so i`m only at about 9.3-1 or so...so no spark knock here..........not alot of power increase,but there is more low end torque...and no the JE piston is staying in..

I was just warning the OP that it can be a problem,having spark knock...

B

Better carb will help,,the XR650R is a decent carb,,but better benifits come from a pumper carb........

I wouldn`t lower/cut the head to get more power.....


If i was going to go rebuild my engine again...i`d get a larger piston...but keep the compression ratio below the 10.5-1.........105 or 106mm ...the larger bore will give more power and no spark knock issues...

Cyclewizard is the guy to ask on that......he may suggest a higher compression ratio than i would,,,,he`s got more experience ..


The NX650 2nd gear is really nice for wheelies i can tell you,,and in tigh woods or sand really makes a difference getting the bike moving..


oh........ consider this too though.......the XR600R had more power than the XR650L........but i think the most difference is in the internal transmission gearing and the final drive (sprockets/chain).........as it came with 14/48 gearing.....
B

Brian,

How is it that when you put an XR piston in the XRL the compression ratio went DOWN? I thought the whole idea of doing the XR piston was to RAISE the CR. Back a couple of years when my XR600 had a melt down (dam kid) I went round 'n round with Thumper Racing trying to get a replacement 102.4 piston for my 6. He kept sending me XRL pistons which have a lower wrist pin to piston crown measurement. I found this out the hard way as I had the piston sent directly to the machinist and he bored the cylinder for it and I put it all together thinking all was good. Turned out the bike ran like a 250. After multiple attempts to figure WTF was wrong I pulled the cylinder only to find that the piston didn't come anywhere close to the top of the cylinder. DUH!!! You state the JE 10.5 piston is giving you 9.3 ?? How's that???

The JE XRL 10.5.1 pistons come to zero deck height or just a few thousandths in the hole .006 to .008 at the most, they yield about 10.2.1 or so then you figure 58cc's for the chamber volume and another 4 cc's for the valve pockets.
So 0.046 for deck height, 62cc's of chamber volume 101mm bore
,82mm stroke leaves you at 10.2.1 compression depending on what the chamber and piston cc's in at.
The XR600 piston sits in the hole more than the XRL's does.
Add .086 for deck height and you have 9.3.1 comp. using it in a XRL motor.

Very good information in this thread!!!