I have been researching off and on for months the possibility of an oil pump upgrade for the RFVC engines using OEM parts. What little information I could find has been inconclusive at best. Some details I recall are that the 650 engines have a wider pump than the 500s/600s and a clutch cover to match. Then again, I have read that all the '88+ pumps are the same. I also just found out that the GB500 has a numerically lower pump drive ratio so it spins slower. Likewise, I have read that there is no difference between any of the pumps. I only have one spare XL600 engine and I don't really want to tear my XR apart just for a comparison.

That said, does anyone have two or more pumps they could compare side by side and report back what they are from and any differences? If there are no differences, I would like to put this one to bed. If there are differences, I think we all could benefit from knowing what they are.

My 650L mil is still strewn about the shop. If you need measurements from a 650L pump let me know the points you want measured.

I have a 650L pump in my parts bin.

What measurements would you like?

The cyclewizard has a few GB and Xbr500's, he modded my oiling system on my first XRL for me it has over 55,000 with no cam or rocker wear. He also built me a new 742 motor with a different pump and lines with a remote oil tank for more oil capacity on my new bike.
He has the answers but won't tell anyone so I don't ask, I'm very pleased with the new motor, it beat my XXR in a drag race.....lol.
You should see his collection of RS600 and 750 race bikes from when he worked with Ricky Graham and Bubba Shobert, they all have special built pumps and oil lines.
He let me ride one of his RS600 flat track bikes and that mother flat out hauls ass. The RS600 came with a big finned head from the factory like the kit that XR's only sells but cast not welded on.

AFAIK, the RS600s had an oil pump specified by HRC, but like you said, they also had a big fin(and single carb!) version of the '83-87 cylinder heads. I have all the engine parts fiches and they sure are fun to look at...

Thanks guys, I'll have to pull the oil pump out of my XL600 engine and see what dims I need...

I have '85 and '98 xr600r motors apart right now.

Let me know what you would like me to measure.

From what I've heard, the NX or Dominator 650 engines from 1994 and onwards (and only them, not XR650L) has a higher capacity oil pump so I suggest you start digging there.

Unfortunately, the new bigger oil pump came with, just as you said, a different side cover that was only available without a hole for the kick starter. It's not possible to fit a older side cover with kick starter over the wider oil pump.

Again, this is what I've heard from an experienced RFVC mechanic.

Good luck in researching, and please post your results here... =0)

torchevo said:

There have been a few folks that have used an XR600R clutch cover on the XR650L after adding a kickstarter, so I'm not sure that's always true.



Dave

XR650L_Dave said:

Read my post again; the XR650L has the smaller oil pump regardless of year, only NX650 (and its derivatives SLR650/FMX650) has the wider pump.

torchevo said:

Yup, I read that wrong.

Curious that the XRL didn't get the bigger pump.



Dave

XR650L_Dave said:

I dont know, but my speculation is that the XR's always been more of a dirtbike compared to NX/SLR/FMX and therefore is more used at lower rpms.
The NX/SLR/FMX commonly sees more street use, and long duration high rpm use, which especially thumperwise is tough on the big end, hence better oil flow/pressure would help.

Just my 50 cents.
But I dont know why honda didn't simply upgraded to the bigger pump in all models.

Here are the oil pump assembly part numbers.

88-89 NX650
15100-MN9-000
15100-MN1-770
15100-MN1-771

93-08 XR650L
15100-MY6-670

85-92 XR600R
15100-MG3-000
15100-MN1-770
15100-MN1-771

93-00 XR600R
15100-MY6-670

83-84 XR500R
15100-MG3-000
15100-MN1-770
15100-MN1-771

89-90 GB500
15100-MK4-600

I guess the trick will be finding part numbers(and people who own parts) for NX650s sold after Honda quit doing it in the US. I don't know what OEM parts dealers there are in Europe or Australia.

I have several XR600 oil pumps.  The oldest is a 86.  I have a 90 and a 93 as well as one or two more of unknown vintage.  I've not measured the 86, but all the others sure looked like they were the same.  I think the 86 is too.  In recently swapped a few parts in my "new" 90 bottom end, but I did not compare to the 93 "old" engine.

Pretty sure most of those assy numbers are just production codes not indicative of actual differences in specs. Does look like the 93 and later pumps are all the same regardless of what they came in.

I don't know if it's any help to ya HT, but here'a a couple pics. Left one is 2000 XR600R, I'm pretty sure middle is '93 XR650L and right is '84 XL600R.

Good thread any new info to add? Are there options for the flexible oil lines?

I have been reading quite a bit about the oiling systems and have come across sever instances where the return line would get kinked tightening it up and reduce oil flow resulting in the top end going south.

zrxer said:

Every little bit helps. I also thought I replied to this thread a long time ago.

Are there any differences in width between the pumps around the rotor areas? Also, am I seeing a bushing for the shaft on the two '90s pumps?

Other than that, the only major differences I see is that the XL pump casting isn't as robust and has one less bolt hole.

Mx760 said:

The hose isn't a problem there, the installer is. But no, there are no aftermarket oil lines. They would have to be scratch built and the engine-side fittings might be hard to find or duplicate.

The hose isn't a problem there, the installer is. But no, there are no aftermarket oil lines. They would have to be scratch built and the engine-side fittings might be hard to find or duplicate.[/QUOTE]

I may resemble the installer being the problem.

One thing I noticed yesterday when working on the oil lines is the oil did not flow too freely through the short line would tend to puddle in the top and slowly drain though could not see in it will try using compressed air to blow it out and see if that helps.

Do all the pumps use the same "orifice" looks like a restricor to build pressure?

i am working on oil feed/supply issues on my XRR. see this thread:
http://www.thumperta...ad.php?t=870563
maybe we should combine these two threads? also, i think we need to identify what we are trying to solve with our research. my personal feeling is that there are deeper issues to the top end/cam failures than just too tight valve lash. i am particularly concerned with the change in level as rpm increases - like i wonder if the B pump is running out of supply oil.....

neil
who is not trying to hijack this or any other thread but is definately following this one with interest