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Lightened Flywheel XR650L?

By pdxthumper,
in XR600R & XR650R/L

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Manos

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The 700xx engine is a cross breed between the XRL and XR650R.

I want to use most of the XRL ignition and mount it on the 700xx motor.

I could use the 650R ignition but has no provisions for a battery and does not have the mounting holes for the starter ring gear/one way clutch.

I’m sorry, I still don’t get this.

Are you mixing and matching parts from the two engines (and is this possible?)

Or you have a hopped up 650R engine run on 650L management (lacking a better word)

M.

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HeadTrauma
HeadTrauma

I will point out that lightening the flywheel will make life harder for the starter, especially with cams that have no compression release. What I would like to do is shorten a 650L crank and put it

Captain Midnight
Captain Midnight

I use a 600 cam cover with manual compression release. I can machine a crank for you.

Manos
Manos

True, but isn’t this comparing apples to oranges? A big part of lightering our bikes’ (big XR/XL etc) is for the hell of it, right? It isn’t for competition riding. Come to think of it, even if a mo

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CFRacer22

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Building a MX/TT setup and need simplify things and lose alot of weight.

The Efi system is ok but not a great system.It has its faults.

Don't know why anyone would ever want to use this bike as an MX/TT platform, no matter how much power you get out of it and weight you shave from it, it will never handle like a 450R...just my opinion, seems like you're putting a lot of work into a project that will never perform well anyway

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Mr Magoo

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Don't know why anyone would ever want to use this bike as an MX/TT platform, no matter how much power you get out of it and weight you shave from it, it will never handle like a 450R...just my opinion, seems like you're putting a lot of work into a project that will never perform well anyway

You can actually make it handle as good or better than a 450r .

I had a built 450r before the 700xx.

But would like some answers to the questions rather than why !:excuseme:

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CFRacer22

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You can actually make it handle as good or better than a 450r .

I had a built 450r before the 700xx.

But would like some answers to the questions rather than why !:excuseme:

Eeehhh, not happening, unless the laws of physics are different over in the UK...the extra weight (125 lbs! and yes, you can shave weight, but so can a 450R), the higher center of gravity, etc.

I've raced the AMA ATVA National MX and TT series here in the US for years now, I'm quite experienced/knowledgeable in the area of getting a quad to handle better...

Good luck with your project though, it's always fun to make something unique!

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Captain Midnight

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Hi

I am working on a pet project on TRX700xx.

The motor is basically a cross breed between the XR650l and XR650r.

I want to run a XRL ignition system or at least try.

The XRL has the pulse pickup on the crank near the cam chain and the 700xx has on the outside of the flywheel.

So the question is could the XRL flywheel be machined down 0.125" and have lobes on the flywheel . This would recreate the pulse pick up ,the same as the XRL.

I hope this makes sense and thank you for any help.

I can do that for you.

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pdxthumper

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Finally had the flywheel dynamically balanced, after turning on a hub mounted shaft total run out was 0.001in, the machine shop that did the balance said it was really close when it came in, and he took just a few small pecks opposite the key way.

So if you do this and you can get the run out down you really don’t need to have it balanced.

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Grand Master

ThumpNRed

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another 5 pounds from what i heard from the guy i bought my bike from. quicker accelleration

There is a five pound difference between the XRR and XRL flywheels. I just wonder if you can shave five pounds off of the XRL with no ill effects. Remember, the ring gear is part of that five pounds so you'd be carving more than five pounds off of the fat part of the wheel itself.

I am very interested to hear from someone who has ridden the same bike before and after. Also very interested in hearing what (if any) effects it may have on the e-start's ability to get everything spinning.

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Grand Master

ThumpNRed

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sorry no e-start. i can tell you what a high comp. piston and after market cam it will literally break your foot if the kick start kicks back

You own the bike that was built by the guy up in NY dont you? If I remember right it has an XRL crank with a reground snout to take an XR600R flywheel and side cover.

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pdxthumper

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How much weight did you have shaved off of the flywheel? Have you run it yet? How does it behave?

The stock XRL flywheel weight without starter gear and bearing: 7.88lbs

Turned down OD XRL flywheel:6.46lbs (-1.46lb)

Stock XR600R flywheel:5.19lbs

I don't include the starter ring gear as it is not spining at engine rpm, due to the sprag bearing.

I haven't put it in yet, so a road test to follow...

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