Are these interference engines? I just found an exhaust valve inside my rt. Cylinder. Stem still in the head. Snapped off at the base of the stem.

The Phantom

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11/77 (edit by GG) manufacturing date. This se has been stored since 1985. 12,000 original miles. I kicked it over 2 times, then engine would not move. I backed up the engine, pulled the right exhaust pipe and saw the exhaust valve was gone but the stem was still in the head under spring pressure. Are these interference engines? I have no idea if the valve scored chamber, piston, head. The bike is new to me. All engine mount bolts are now loose, will pull the engine tomorrow.
I would appreciate some experience and expertise here/ in the future.
 
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11/87 manufacturing date. This se has been stored since 1985. 12,000 original miles. I kicked it over 2 times, then engine would not move. I backed up the engine, pulled the right exhaust pipe and saw the exhaust valve was gone but the stem was still in the head under spring pressure. Are these interference engines? I have no idea if the valve scored chamber, piston, head. The bike is new to me. All engine mount bolts are now loose, will pull the engine tomorrow.
I would appreciate some experience and expertise here/ in the future.
According to Roger Johnson (The machinist for Gary Hoos), valve heads snapping off is not uncommon. He insists on replacing them with stainless valves. As to it being interference or not, someone way smarter than me will be along shortly. Good luck.
 
I believe that 99.9% of all somewhat recent OHV motorcycle engines are "interference engines". Motorcycle engines generally are in a higher state of tune than car engines, which means larger valves, higher valve lift, and mostly higher compression ratio. These features all reduce internal clearances.
Car engines that are "non-interference" are most likely low performance, low fuel efficiency, or turbo/ supercharged.
 
Thinking out loud here a bit to tight Valve Stem / Guide clearance on these machines ??
Or is it the storage only .?
Fairly low mileage and maybe no wear ... Heard it before here on the forum after rebuilds valve stops moving
Start up prcedure low mileage after long standstill ? heating from the outside ? chemicals ? topping up with oil for some time ? ?
 
Hi Phantom, sorry to hear about your predicament. You've definitely come to the right place for help & advice. I'm interested to know how much you know about the engine - was it running when the bike was originally stored or perhaps that's why it was put aside? Have you heard the engine run? How did you know to pull the r/h exhaust first?

You will indeed indeed need to take the engine out to remove the rocker box and cylinder head. My guess is you'll only be able to assess the damage once you open the engine up. Best case, if the valve got stuck during storage, then there's only your kicking attempts which are relatively low-speed and the damage might just be the valve. Obviously, need to take a good look at the top of the piston and see how hard it got clouted.

You got somebody to help you lift the engine? Doing yer back in lifting it will hardly help . . .

Good luck, Raymond
 
As the valve apparently stuck while "waking from storage" and contacted the piston, it was likely gummed-up and had no lube. A valve job -possibly with new guides is in order - below are specs for guide/stem clearance. Must cut new seats if guide is replaced.
1695211740139.png
 
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They all are when a valve sticks open. Pretty high odds that's what happened to you.
Yeah, thanks. I did open the access plate for that valve before kicking it over. The rocker was very loose. I didn’t know that meant stuck valve.
Hi Phantom, sorry to hear about your predicament. You've definitely come to the right place for help & advice. I'm interested to know how much you know about the engine - was it running when the bike was originally stored or perhaps that's why it was put aside? Have you heard the engine run? How did you know to pull the r/h exhaust first?

You will indeed indeed need to take the engine out to remove the rocker box and cylinder head. My guess is you'll only be able to assess the damage once you open the engine up. Best case, if the valve got stuck during storage, then there's only your kicking attempts which are relatively low-speed and the damage might just be the valve. Obviously, need to take a good look at the top of the piston and see how hard it got clouted.

You got somebody to help you lift the engine? Doing yer back in lifting it will hardly help . . .

Good luck, Raymond
This se was an auction piece by previous owner. Manufacturing date is 11/77, so I guess it’s a 78 model. Matching frame and engine. Previous owner never heard it run, but it sat indoors 38 years.
I guess I’ll put a new timing chain and I’m not sure about the rest of the top end. All new valves. Seats? I don’t know. I won’t pull the cylinders if no damage, but I don’t know. I believe the 12,000 mileage is valid. Any help would be greatly appreciated. I’m in no hurry.
 
I guess I’ll put a new timing chain and I’m not sure about the rest of the top end. All new valves. Seats? I don’t know. I won’t pull the cylinders if no damage, but I don’t know. I believe the 12,000 mileage is valid. Any help would be greatly appreciated. I’m in no hurry.
Chances are very good that valve guide is damaged, or caused the valve damage or both. I'd have the head gone through or find another head to replace that one (probably cheaper).

As far as removing the cylinders, you're pretty much commited to that because the base gaskets been compromised when the head was removed and requires replacement. That will mean a light hone job and new rings at a minimum.
 
Chances are very good that valve guide is damaged, or caused the valve damage or both. I'd have the head gone through or find another head to replace that one (probably cheaper).

As far as removing the cylinders, you're pretty much commited to that because the base gaskets been compromised when the head was removed and requires replacement. That will mean a light hone job and new rings at a minimum.
Thanks
 
Hey, I’m pretty interested in making this se right. My past auto experience tells me to replace seals due to the age and the fact this engine will be taken apart. I’m not too interested in going into the bottom end though.
What seals do y’all suggest? I also don’t have a manual, which do y’all suggest and from where? I also need part dealers. Closest Yamaha dealer is over an hour away, and they don’t seem interested in older models.
Do I refer to this as a 77 or 78? I get the impression 77 was a good year where some advances were made to previous design. 11/77 is the date on the frame tag. Thank you for your suggestions.
One more thing, the tank is in great shape inside but a minor dent about 5 inches long/ 3 inches wide on left side. I don’t want bondo because it’s too deep. Maybe a fiberglass filler? What do y’all recommend?
 
Pics would help but that build date is a 78 model, if it's got mag wheels and a disk rear brake it's the first year for the special. Matters not for engine parts, the carbs will be different, 78 with 5 holes in the intake bell are better.
 
Reverse order.....
Todays Bondo ain't your grandfathers Bondo. It'll work just fine.

11/77 makes it a '78
Look in Tech. Manuals are available there for download. I just use the Yamaha manual.... don't trust the others.

Parts....
How's your bookmark finger?


https://www.cruzinimage.net/

https://www.partshark.com/oemparts/partsearch/suzuki?partsearch=13651-51010

https://www.mikesxs.net/

http://650central.com/

https://www.nospartsnow.com/yamaha/

https://www.partzilla.com/catalog/yamaha/motorcycle

https://yamahaxs650.com/

https://www.diablocycle.com/

https://www.georgefixs.com/yamaha/

http://vintageconnections.com/

https://xs650direct.com/

Google in-site search function.... site:xs650.com (space plus search criteria) For instance... site:xs650.com jim
 
Should have added....
Make sure you ask here before buying. We have combined many years of experience with these vendors and mostly know what's good and what's garbage.

MikesXS. Think of them as a last resort. Some of their stuff is OK, but way too much of it's Chinese junk. Ask before you order.
 
Should have added....
Make sure you ask here before buying. We have combined many years of experience with these vendors and mostly know what's good and what's garbage.

MikesXS. Think of them as a last resort. Some of their stuff is OK, but way too much of it's Chinese junk. Ask before you order.
I’m new to this machine but bought it because of the international interest. I have worked on various vehicles since 74, so I can appreciate those who have the ins and outs of this product. Thanks so much. I thank you for the support.
 

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Pics would help but that build date is a 78 model, if it's got mag wheels and a disk rear brake it's the first year for the special. Matters not for engine parts, the carbs will be different, 78 with 5 holes in the intake bell are better.
Hi Gary, yes it has one disk in the rear and I do believe the carbs have 5 holes. I’m going to need both master cylinder’s and I guess it’s possible to hone the calipers and put new rubber in them, I don’t know. The pecocks on the tank, can they be rebuilt? I’ve got time this winter to try and get this thing right. Oh, and mag wheels. I’m going to need new tires as well. Don’t know which. What would you suggest?
 

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