1991 XR600R Cylinder Head Compatibility Years??


3 replies to this topic
  • richklutz

Posted August 26, 2007 - 10:32 AM

#1

I bought an XR600R that was abused pretty bad by a previous owner and decided to take it on as a project hoping for the best and of course going way over budget. I completely disassembled the bike and sent the motor to AMI in Puyallup for cylinder resleeve and a rod kit. They told me the head was about to go and I decided to risk it and put it together and hope to not have to spend any more money for at least 2 or 3 rides. Wrong.

The bike is dumping oil in to the chamber after startup and I'm sure I should just replace the un-rebuildable (according to AMI) head. Now, I found some parts on eBay and Craigslist, etc., but get mixed information over head compatibility. Some say '88 to late 90's fits my bike, but when I see closeup pictures of older heads they don't look different (like '86). Of course some bikes have black motors, while mine is unpainted aluminum, but other than that what's the difference?

I want to ride when September finally delivers the weather we've been expecting all summer.

  • Horri

Posted August 26, 2007 - 03:26 PM

#2

While I don't know about the cylinder head compatibility I can tell you that the 93 bottom end,,Gearbox etc are exactly the same parts as go into the 86.I have an 86 so am always interested in bits.Later today I'm going out the the Honda dealers to see how much a New Stator is so I'll get the guys to check the parts manual and see if the head part numbers are the same.I'd doubt they would be,but I'll post back the results.
Edit:::Bike shop guys are not keen on giving out the info with bosses around. The part number books are like Enigma Machines..Why I do not know. 24hrs and I will have the full story on the 80's-91 and 93 Sorry about that.

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  • cleonard

Posted August 27, 2007 - 11:12 AM

#3

The main difference is the single vs dual carb setups. The earlier bikes are all dual carb so just be sure that you get a single carb head.

Depending on what is wrong with you old head, XRsOnly may be able to fix it. They have fixed a head for me that a local shop declared dead. Give them a call and ask about it.

  • crmc33

Posted August 28, 2007 - 04:13 AM

#4

All the 600 and 650 RFVC heads are similar and are interchangeable to a large extent.
The cyl head dome sizes change (gives more or less compression), the decompressor systems changes (XRL/XL/XR stlyles) and the cam lobe spacing is often different. Hence its important to have a matching head and cam cover as the cams and lobes wont meet up!
The later XRL cam chain and sprocket is also different. For example, my XR650L (NX650) takes a wider camchain than the earlier lighter type on the XBR500.

The early XL/XR cranks are also a lot lighter than the later style as used on the XRL (The XL600 has wasted crank webs for example - revs much faster than a XRL!)

AFAIK, the valves and springs are all pretty much identical. The early heads tend to crack btwn the exhaust ports and the spark plug hole.....then the valve seats fall out ......ouch!

Lots of other changes in gearbox, selector direction and primary drive ratios as well of course.

Amyway, I hope this helps!





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