RX3: Engine Top End Rebuild at 22,450 Miles

[SpudRider]

Originally Posted by jbfla

...Were you able to examine the valve seat once the valve was removed?...

jb

Since the valve recession was obvious, I didn't remove any of the valves for inspection. I wanted to ship the untampered cylinder head to Gerry for his inspection. I also didn't care to do the extra work.

[pete]

Originally Posted by jbfla

I hope it is an isolated case, too.

While out riding today, I was thinking that most recreational RX3 riders, more than likely, ride 10,000 miles a year or less.

By the time they get to Spud's mileage, the bike will be out of warranty...

jb

parts are made in batchs not one offs..... So if it's not a assembly issue
from the factoy !!!
Spuds bike was one of the first so any other bikes in the same shipment
could have parts from the same batch...
So read into that what yer want...



....

[jbfla]

Thanks Jay and Pete.

Pete, what do you "read into that"?

I was hoping Spud still had the cylinder head.

It shouldn't be too difficult to have a lab do a hardness test on the valve seats.

I suspect my RX3 engine has a similar condition, in addition to other problems.

At ~8,500 miles both intake valves went to zero clearance within 1,000 miles. The lock nuts on the threaded adjusters were still tight.

My RX3 is from the second US shipment.

As of now, I have decided to "test the engine to failure".

Then I will open it up to see what is going on.

jb

[jbfla]

Originally Posted by SpudRider

....... I wanted to ship the untampered cylinder head to Gerry for his inspection.......

Did Gerry contact you after his inspection?

jb

[SpudRider]

Originally Posted by jbfla

Did Gerry contact you after his inspection?

jb

Yes, of course we chatted after he received the cylinder head. As I could tell from a visual inspection, he verified the intake valves had significant valve recession. He also said CSC was contacting Zongshen regarding this issue. We arranged for the delivery of the replacement parts, et cetera. I rebuilt the engine, and I have not chatted with him again regarding this matter. With over 3,000 miles ridden since the repair, the engine is running great.

Soon I am going to purchase more items from Taobao. Among those items I am going to order a spare, empty cylinder head for 320 Yuan ($46.39 USD). As long as one is capable and willing to do the engine repairs, the replacement parts from China are very inexpensive. Here are two links to Taobao vendors selling the cylinder head.

https://item.taobao.com/item.htm?spm...cket=20#detail

https://item.taobao.com/item.htm?spm...cket=20#detail

[jbfla]

Thanks for the info, Spud.

I am glad to hear that CSC is contacting Zongshen about the issue.

jb

[SpudRider]

Originally Posted by jbfla

I hope it is an isolated case, too.

While out riding today, I was thinking that most recreational RX3 riders, more than likely, ride 10,000 miles a year or less.

By the time they get to Spud's mileage, the bike will be out of warranty...

jb

I am truly sorry to be the bearer of bad news.

In case anyone wonders, I do not work for CSC Motorcycles. I paid the same price as everyone else for my RX3 motorcycle, and I have never received any monetary compensation from CSC. I am merely a fan of Zongshen motorcycles, since I own a ZS200GY-2 with almost 80,000 miles on the odometer, and a ZS250GY-3 with over 25,000 miles on the odometer. I bought my first Zongshen motorcycle in 2008, long before CSC became the dealer for these motorcycles in North America.

I certainly don't want to harm CSC motorcycles. Quite to the contrary, I wish for them to succeed. CSC Motorcycles is an honest business which provides excellent customer service. Indeed, I was somewhat reluctant to post this thread. However, I believe very few riders in North America have logged as many miles on an RX3 motorcycle as I. Therefore, I felt a moral obligation to report this problem.

I posted this thread as a friendly warning for others to be watchful for this problem. I don't have a crystal ball. Therefore, I don't know if anyone else is going to encounter this problem. It is impossible to manufacture every vehicle perfectly. Many excellent vehicles from many different manufacturers, both foreign and domestic, have occasional mechanical problems. Only time will tell whether this particular problem with this particular vehicle is rare, or not.

The Zongshen RX3 is not the only motorcycle with this engine. The NC250 (ZS177MM) engine is installed in a number of different street bikes and dirt bikes sold by Zongshen and other manufacturers. Surely many Chinese owners of the RX3 motorcyle have logged more miles than I. Nevertheless, I haven't heard of this problem occurring before. Perhaps this problem has occurred previously, but I am unaware of it, personally.

If the NC250 engine has problems, I'm confident these problems will be resolved by Zongshen, and honestly covered under warranty by CSC Motorcycles. Therefore, if anyone suspects he is having this problem, I strongly encourage him to to take advantage of the excellent warranty coverage offered by CSC.

[SpudRider]

Originally Posted by jbfla

Thanks for the info, Spud.

I am glad to hear that CSC is contacting Zongshen about the issue.

jb

You're welcome.

[SpudRider]

Doing a little more searching on Taobao, I found an empty cylinder head selling for 270 Yuan ($39.15 USD).

[2LZ]

Spud, do you have ethanol gas up there? I know it's hard on rubber parts but it can also cause engine damage by increasing exhaust temps.....which would directly effect the valves.

Odd thing is my intakes never needs adjusting, just the exhausts. Of course, I don't put on the miles you do.

[rjmorel]

Question about receding valves? What are the causes? Is the valve seat hammering into the aluminum head? Seat hole in head machined to deep allowing it to get hammered in farther till it bottoms out in hole? Seat or valve material to soft so angles wear out prematurely. Running bad gas? Freeway driving where throttle is close to wide open most of the day?
I take it ,it mostly isn't something an owner would do to cause it?
Can't say how my vales are behaving cause I think I went about 7000 miles between last adjustment and it ran fine, but was occasionally dying when coming to a stop on Baja trip. Had CSC adjust them when we got back and runs great at 14,200 miles on it now. Mine was 2nd batch when price went from $2895 to $3495. Still the most fun money I've ever spent. rj

[jbfla]

Originally Posted by SpudRider

I am truly sorry to be the bearer of bad news.....

Therefore, I felt a moral obligation to report this problem.

....I posted this thread as a friendly warning for others.....

Thanks for your thoughtful reply.

I don't think of it as being a bearer of bad news, but as something that rider's should be aware of....

....especially on a product that is expected to be "rider maintained".

As a consumer, I want as much info on the product as possible. Both good and not-so-good.......and to know if a problem is a simple fix, or more involved and costly.

I hope people don't misinterpret all my questions as being negative to CSC.

Quite the contrary. CSC has consistently gone above and beyond in supporting the RX3.

However, in one of CSC Dude's blog posts, he said that they would prefer problems to be discussed directly with CSC, and NOT on the "forums".

I think open discussion is beneficial to solving problems.

For example:

Because of open discussion, I was able to correct several potential issues on my DR 650 that could have become serious and expensive problems.

...neutral indicator bolt
...counter shaft seal retainer
...upper chain roller

All simple fixes, if done before they become an issue.

Not sharing this information would have been a disservice to DR owners.

IMO, reporting issues openly, by actual owner/riders, not the "keyboard commandos", is beneficial to all owners.

jb

[SpudRider]

Originally Posted by 2LZ

Spud, do you have ethanol gas up there? I know it's hard on rubber parts but it can also cause engine damage by increasing exhaust temps.....which would directly effect the valves.

Odd thing is my intakes never needs adjusting, just the exhausts. Of course, I don't put on the miles you do.

Yes, we have 10% ethanol fuel up here. I think there is one gas station in town that sells fuel without ethanol. I frequently ride in the mountains around a resort town about 30 miles from here. A convenience market there recently added two fuel pumps dispensing non-ethanol fuel. I was there one day when a middle-aged gentleman from Utah came inside the store and asked what was special about non-ethanol fuel. Apparently he never saw non-ethanol fuel offered for sale anywhere in the Salt Lake, greater metropolitan area.

Your two RX3 motorcycle came on the first shipment from China, just like mine. It's interesting that your intake valves have stabilized, but your exhaust valves have not, while my experience was just the opposite. I'm tempted to experiment with one of the fuel additives, especially the Lucas UCL (Upper Cylinder Lubricant), but I also want to see if the valve lash will stabilize in the new cylinder head without using a fuel additive.

[SpudRider]

Originally Posted by jbfla

Thanks for your thoughtful reply...

As usual, you are welcome.

Originally Posted by jbfla

...As a consumer, I want as much info on the product as possible. Both good and not-so-good.......and to know if a problem is a simple fix, or more involved and costly.

I hope people don't misinterpret all my questions as being negative to CSC.

Quite the contrary. CSC has consistently gone above and beyond in supporting the RX3...

I don't interpret your questions as negative. Your questions are a natural response to gain information about possible problems with a motor vehicle you own. Contrary to being negative, I regard you as one of the most active, helpful, and polite members of this forum.

I also agree with your positive comments regarding the customer service from CSC.

Originally Posted by jbfla

...However, in one of CSC Dude's blog posts, he said that they would prefer problems to be discussed directly with CSC, and NOT on the "forums".

I think open discussion is beneficial to solving problems.

For example:

Because of open discussion, I was able to correct several potential issues on my DR 650 that could have become serious and expensive problems.

...neutral indicator bolt
...counter shaft seal retainer
...upper chain roller

All simple fixes, if done before they become an issue.

Not sharing this information would have been a disservice to DR owners.

IMO, reporting issues openly, by actual owner/riders, not the "keyboard commandos", is beneficial to all owners.

jb

I haven't read CSC Dude's blog post regarding that matter. However, as you stated, virtually all motorcycles have some mechanical issues which need to be addressed. Naturally, all owners of those motorcycles wish to be made aware of any potential problems. This is a normal reaction for any wise consumer, especially the purchaser of a motor vehicle. Therefore, I agree completely with all your comments.

I knew you were having some mechanical issues, and I also knew you were nearing the end of your warranty coverage. Therefore, I felt morally obligated to advise you, and others in your situation, of the possible consequences which might occur if your valve clearances will not stabilize. I appreciate the excellent customer service from CSC, and I truly want them to succeed and prosper. However, I feel an even greater obligation to my fellow RX3 owners, such as yourself.

I have had several mechanical problems with my RX3. You might remember the problem which occurred when the crankshaft nut loosened, and cracked the right crankcase on my motorcycle. As far as I know, nobody else has encountered this problem, probably because CSC notified everyone else and advised them to perform a maintenance check at 10,000 miles. As with resolving that problem, I also didn't want to perform a top end rebuild of this engine. However, to their credit, in both instances CSC honored their unlimited mileage, 2-year warranty.

Many of us on this forum, and other forums, have contributed a great deal to the improvement of the CSC Cyclone RX3. We are dedicated enthusiasts of this motorcycle, so we naturally will continue to inform fellow owners of potential problems, upgrades, and modifications. This normal process of sharng information is universal for owners of all motor vehicles from all vendors, whether big or small, foreign or domestic.

Despite having several mechanical problems, I am still glad I purchased a Zongshen RX3 motorcycle from CSC. The more I ride my Zongshen RX3, the more I enjoy riding it, especially after I installed the lighter spring (now standard) on my Progressive shock, and switched to a 21-inch front wheel.

[katflap]

Spud, what a bad stroke of luck, that sucks.

but resulted in a great tutorial from you

There is a detailed service manual available on the AJP website for the PR5, you and others already know, It uses the same engine as ours. so is seems quite relevant.

(I don't think we have had this one on here before )

It contains a number of procedures, specs, service wear limits and torque settings in regards to the engine and fuel system.

It Might serve as a good companion to your tutorials.

http://motoajp.com/ajp-support/pr-service-manuals/