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&[email protected]^)#!$!!! Put about 1500 hard kilometres on my 93 Dommie last weekend and neglected to check the oil levels. Got it home and changed the oil and I'd be lucky if I could get 500ml out of it. With fresh oil in it I took it for a ride, and it's definitely down on compression though how much I won't know til I get to work tomorrow as my comp. tester is there. Blowing a bit of smoke but nothing too bad, though it's obviously only going to get worse not better.I love the bike to bits and it's got some great other gear on it like a 30L tank and fresh adjustable custom suspension so I'm happy to put a bit of cash into the engine as I plan on keeping it for a fair while yet.

So I guess it's time to start hunting round for a rebuild kit, probably a big bore kit. Are the XR650 ones the same or are there any differences? It's got a reground cam and a Staintune already and goes pretty decent but more power's always good. Any suggestions on who to speak to about bits would be great, thanks.
 

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Also, this'll be the first time I've rebuilt a bike engine, what should I be aiming to do? I'm figuring I'll pluck the engine myself and give it to a shop to fit the new piston/rings and hone the bore if its needed, plus might as well fit new valves and seats while it's out. What else would you do while the engine's on the bench?
 

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Also, this'll be the first time I've rebuilt a bike engine, what should I be aiming to do? I'm figuring I'll pluck the engine myself and give it to a shop to fit the new piston/rings and hone the bore if its needed, plus might as well fit new valves and seats while it's out. What else would you do while the engine's on the bench?

Hi sorry to hear about your bike,

im just finishing a rebuild for the same reasons.

i spent ages on the net researching how to get more power out of an nx engine and here pretty much what i found out....

Wiseco lie about the piston compression on their forged piston and its pretty much the same as standard only £50 more expensive there are plenty of forum threads on this on the net thumper talk etc.

JE dont have an exact fit for the NX (something to do with the gidgeon pin being a different size and you have to buy spacers from germany)....sounds like a job best left alone

the cam on the nx650 is the same as the xr650l so if youve had yours reground for more poke then leave it as it is

change the valve seals whilst its open but im not sure id bother with the stems as these engines are supposed to be bomb proof

De-smog kit your engine as it will make it run smoother

if i was you and i was looking for more power id rebore to plus .50 which i think equates to in the region of 670cc (this is the maximum you can rebore the cylinder) and order a piston from Honda san, id then buy a jet kit (dynojet etc)

if your looking to step up in performance after that then your risking reliability, go to google and type in "building a better dominator"


the only other thing id consider is ...possibly fitting an oil cooler as the guys on here and other forums seem to have the odd worry about oil temp.

i hope this helps you and saves you hours of research

Regards

Zippy :thumbup:
 

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Fantastic info, thanks for that Zippy. The bike's built as a desert crossing machine which is what I want out of it, so I'd rather reliability than power. Your comments make me think factory is the way to go (assuming the bore is okay and doesn't need much honing). Guess the other thing with more power is more using of that power and less fuel range too!

I'm not spewing about it, I look at it like a good learning experience, especially since I have another vehicle to get around in no dramas. Can I ask what you spent on the entire rebuild and how much you did yourself?
 

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Fantastic info, thanks for that Zippy. The bike's built as a desert crossing machine which is what I want out of it, so I'd rather reliability than power. Your comments make me think factory is the way to go (assuming the bore is okay and doesn't need much honing). Guess the other thing with more power is more using of that power and less fuel range too!

I'm not spewing about it, I look at it like a good learning experience, especially since I have another vehicle to get around in no dramas. Can I ask what you spent on the entire rebuild and how much you did yourself?

i did it all my self except for the rebore/hone and it went something like this...

Haynes Xr650 manual as it covers this engine 20

gasket set 60

piston 100

rings 30

circlips 2

bore and hone 30

i had to buy some tools aswell torque wrench and valve compressor etc which cost me a bit, if you dont have these tools it sends the rebuild costs up but it makes your tool kit better.

i also got brave and bought a dremel and ported and polished the head and i have to be honest im pleased with the resuts and im sure till make a difference to the performance of the bike but its a pretty brave move ...helpfully there are guides on youtube to help ...but be certain you want to try this before getting in to it as it can be a bit daunting!

oh by the way all prices are in british pounds sterling!
 

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If you ran it low on oil, you'll have top end problems (valve stems and valve seals), valve, rocker arm and camshaft wear, camshaft bearings wear, piston seal wear and worst of all, crank bearing wear. Possibly clutch wear as well; maybe some problems with skirt & piston, but this is avoidable. Just a quick checklist off the top of my head.
 

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If you ran it low on oil, you'll have top end problems (valve stems and valve seals), valve, rocker arm and camshaft wear, camshaft bearings wear, piston seal wear and worst of all, crank bearing wear. Possibly clutch wear as well; maybe some problems with skirt & piston, but this is avoidable. Just a quick checklist off the top of my head.

i have to add to this that my nx was indeed run low on oil and and all the damage was to the bore / piston there was no damage to my cam or rockers

why this is i dont know

the big end bearing was also ok maybe this has something to do with the pool of oil that sits in the bottom of the engine ....or maybe my engine wasnt run as low as to damage these

i dunno its a mystery ..but i know my crank and cam is fine!
 

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It's a checklist, not a guaranteed damage list. :)

But a dommie with ok compression, ridden HARD on low oil will screw the top end over with little to no damage to the piston/skirt. Piston rings were replaced by default after disassembly.
 

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It's a checklist, not a guaranteed damage list. :)

But a dommie with ok compression, ridden HARD on low oil will screw the top end over with little to no damage to the piston/skirt. Piston rings were replaced by default after disassembly.

switch,

Stop it, your making me nervous! :toothy9:
 

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Chillax, I also know of a dommie with about 7-800mL of oil (bugger used the almost empty oil canister instead of the right one) which ran for about 600km @ 75+mph and the only damage was like 10% loss in compression - probably due to piston ring wear. Probably some premature wear in other areas, but nothing to fear there. The bike still runs and is nearing 70k km (some 40-50k miles), with the incident happening at around 45k km. :thumb: Bike doesn't smoke or drink oil, (more than usual).
 

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Discussion Starter #11
Thanks for that info. She's definitely smokey when cold, once warmed up it starts to settle down. Gonna try a few heavier weight oils and see how it goes.
 

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on the subject of oil changes, I changed the oil and filter before setting off back to UK from Budapest last week, and the maunual said she shoul dtake 1.9l. I got 2.6l in and it just reached 'high'on the dipstick. does anyone know why this is?

meanwhile. checking oil in Austria it had dropped a fraction so checked how much a litre was as a spare - 1 litre 10w-40 4T cost 36euros!!!! still halfway between high and low, only 200miles or so to Malvern now where I have some sitting waiting!
 

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You didn't check the oil in the proper way. If you keep filling with the bike on the sidestand, you can pour about 3L in there. But a proper check will reveal a way-beyond-max level. Excess will spill into the airbox and be burnt by the engine.

If you pour in 2L, you're fine. More - not a good idea.



1. Run the bike 'till it's at normal operating temp.
2. Pull over and keep holding the bike straight (not on sidestand or centerstand)
3. Keep idling the bike for half a minute.
4. Stop the engine and wait another half a minute.
5. Check the oil by inserting the dipstick WITHOUT screwing it in. You've been holding the bike straight (sit on it) this whole time, yes?

Feel free to repeat this a few times for an average reading. One measurement is never enough.
 
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