Topic: CB750: Aware of cheap parts -tensioner rubber cracked in 2- Carb boots cracking

[PeWe]

I got a small and big  surprise today when removed the head and was going to remove the cyl block.
1.)
The cam chain tensioner upper wheel had cracked in 2 pieces. The 2 rubber parts were blocked between tensioner and cyl side above the tensioner adj hole.

The tensioner had around 5500kms + revving when adj carbs. Lets say max 6000kms which is nothing. The old Honda tensioner had 35.000kms and still instact except for the hard rubber and the usual rubber rubbing.

I checked my old receipts so I do not say wrong. Tensioner was Cam chain tensioner kit from vintagecb750.com bought summer 2012. I remember that I saw a label with made in Taiwan. I had that in my mind and had plan to replace it this winter. New Honda tensioner waiting in a box with many bags and boxes marked with Honda.....

I did not had in my mind that the wheel should crack in 2. The rubber parts blocked the tensioner which explain the hard chain at last cam change. Removal of tensioner adjuster did not release as much I rembered it should. I blmaed the new HD cam chain...

This means that the wheel broke at around max 3000-4000kms!!!!   Real crap!!!
The only thing I can say to all that has installed this crap: Pull engine and install the correct thing before it turns expensive. I doubt this is one single case. Wrong type of rubber

2.)
Before  when removing my carbs. Cracked carb boots. The very cheap ones from Cruzinimage. I tested to see if they should keep together. For that price probably not and I was right. These have around 2000kms. 2 of the boots with deep cracks.
I have used same clamps on my OEM carb boots that have no cracks at all with OEM carbs and around 35.000kms.
I planned to replace them. I have NEW Honda carb boots waiting.  Fuel used all the time is Shell V-power. Maybe strong stuff?
 Cheap China fuel hose will not withstand either. Replaced by real USA made fuel hose from Gates that is OK, Barricades.

[madmtnmotors]

Damn. 

Sorry for your pain, thanks for the review. I had similar issues with CI's carb kits (non-Viton).

[harisuluv]

Preaching to the choir.  There are some people that are just willfully ignorant in regards to cheap parts.  They want to believe they are good parts.  Looks like the original part?  Just as good.  Anyone who actually thinks that aftermarket cheap chinese parts are GENERALLY (I repeat GENERALLY) equal to or better than OEM needs to have their head examined.

In SOME cases, they aren't even significantly cheaper, either. 

I have warned people about those boots in particular, they are obviously made out of a different rubber.  The real ones are also reinforced with a fiber weave which makes them stronger.  Cheap chinese ones are just cast rubber, with a cheap compound.  I have no doubt they will degrade faster and their fuel resistance is also suspect.

Despite being extremely clear with the words "generally" and "in some cases," I'm sure someone will still feel the need to point out that SOME parts are just as good or that aftermarket parts are always cheaper.  Please do not confuse the exception to the rule with the rule.  Please do not point out that you could point to all sorts of chinese parts that are well manufactured, even in industries not limited to reproductions like we are talking about here.  I know this, we all know this. 

TLDR  Cheap Chinese parts suck.  Buyer beware and buy quality.

[disco]

Ouch! It's that old saying.... you get what you pay for.

I did not like CI's engine gasket set.  Admittedly it was cheap, but gaskets appeared very thin. Also head gasket holes were not punched exactly right & it would not fit well. I decided not to install this & to buy Yamiya. What a difference! Perfect fit & much thicker gasket like original Honda. Lesson learned.....pain of extra $$ for good quality is worth it.

[PeWe]

Boots are easier to see when cracking and replaced within an hour or 2. Worse with the cam chain tensioner that need an open chain. I will not open cam chain, cases to be apart.
I was lucky when I cannot see any damage and cases to be apart anyway. I had to warn others.

The metal cam chain tensioner might be a better choice, no rubbers that can crack or be found as small parts in the oil pump mesh.
http://www.ebay.com/itm/Honda-CB250-CB350-CL350-SL350-CB750-Cam-Chain-Tensioner-Roller-Wheel-Set-/231576401099

[Garage_guy_chris]

Thanks for the heads up on the boots I also have a set in use and ive got something fishy going on with carburetion. I will have to check mine for cracks. I just priced OEM boots from honda canada and they are available and reasonable enough price wise im probably gonna get a set.

Hey Pewe: How do those cruzin_image boots fit? Mine don't seem to fit worth a crap. my airbox is up against the frame at the back and its very hard to get the mounting holes to line up

the Shell V power (at least here in Canada) should be 100% gasoline with no alcohol its also regarded as top tier gas

I don't mind taking a chance on cheap parts provided they are easily accessible and easy to replace. My logic with the Cruzin_image stuff was the piston kits work well enough how bad could the other stuff be.

[harisuluv]

My logic with the Cruzin_image stuff was the piston kits work well enough how bad could the other stuff be.

Yeah this is a common reasoning on the "cruzin" products.  However, it is very likely that the products don't really have anything to do with each other.  Different manufacturers, quality control.  Cruzin is just a vendor.

[Wingnut74]

Oh Man, just finished tightening up the head with that same VintageCB750 cam tensioner. I used NOS +1mm pistons, rings, pins, head gasket and timing chain and for some reason it never crossed my mind to track down NOS cam tensioner. Its funny (not really though) I recall the made in Taiwan on the bag it came in. DOHH!! Having never done it before and being totally paranoid about damaging rings and new bore job, it took me forever to get the cylinders on. I am hoping that maybe this was an unusually isolated defect and that others have used this part without issue? This was the only instance of failure I could find. Any other failure experience on this one? Anything weird that could have happened internally that could do this to a good product? thanks

[grcamna2]

Boots are easier to see when cracking and replaced within an hour or 2. Worse with the cam chain tensioner that need an open chain. I will not open cam chain, cases to be apart.
I was lucky when I cannot see any damage and cases to be apart anyway. I had to warn others.

The metal cam chain tensioner might be a better choice, no rubbers that can crack or be found as small parts in the oil pump mesh.
http://www.ebay.com/itm/Honda-CB250-CB350-CL350-SL350-CB750-Cam-Chain-Tensioner-Roller-Wheel-Set-/231576401099

These aftermarket parts look good,chromoly USA steel rollers,what's not to like? ! 

[madmtnmotors]

Oh Man, just finished tightening up the head with that same VintageCB750 cam tensioner. I used NOS +1mm pistons, rings, pins, head gasket and timing chain and for some reason it never crossed my mind to track down NOS cam tensioner. Its funny (not really though) I recall the made in Taiwan on the bag it came in. DOHH!! Having never done it before and being totally paranoid about damaging rings and new bore job, it took me forever to get the cylinders on. I am hoping that maybe this was an unusually isolated defect and that others have used this part without issue? This was the only instance of failure I could find. Any other failure experience on this one? Anything weird that could have happened internally that could do this to a good product? thanks

I have been motivated to tear down my most recent build based on this information, since I used the same tensioner components from Vintage CB750. I have about 1500 miles (2400km) since the rebuild so once I get the top end back off I will report my findings back here (probably before the end of the week). New Honda tensioner parts are on the way, so once it's back together I will be able to (once again) ride with confidence.

[bwaller]

It's a bloody problem, friggin junk.

[Jerry Rxman Griffin aka MuthaF'er]

I certainly hope these things are reported to the vendors including a link to this thread!

I just received an order from VintageCB750. Seemingly 'innocent' items. A replacement F wire harness unavailable anywhere else, battery and solenoid cables, throttle cables 1/3 the price from Honda. All state 'made in Taiwan'. Hoping for reliability. Just installed my carbs with new Honda boots. New Honda cam chain tensioner and discontinued primary tensioner. Gotta pick your poison here boys. Sometimes we do NOT have a choice since Honda doesn't wish to help us by licensing products to others for items they no longer wish to supply.

[PeWe]

Electrical stuff like harness will most likely work. if not easy to repair.

Talking about electrical stuff...check the insulation around the pins/sockets. It must be properly attached (melted/crimped)
I also ordered Rear Brake Light Stop Switch just for sure, the old one was just old and dirty but fully functional after 97.0000kms and several tear downs of the entire bike.
I got 2 stops in the evenings before I found the insulation around the connector loose. Clear tube came lose and connector against the engine or frame bolt.  Short circuit when braking.

I was lucky both times when I was 25m from my friend living 20km from town among rednecks, the other time 25m from my home. I had not many fuses left then. This was when I understood the brake circuit use the 15A fuse. Bad Honda! Bike will stop and light off direct
This was bad part ordered mars 2013. Spring 2014 was the year when bike was out on the street again.
Same place more twaiwan stuff rubber strap holding the battery dried out completely and went off after a year. I thoutgh my sealed GEL battery leaked. But I had Taiwan in my mind and ordered Honda strap. Still Ok after a year.

I got a rear brake switch in Honda bag from David silver today together with NOS front fender.

One more thing was the coils shipped with Pamco ignition. Ignition wire just popped out from the coil when the sharp screw just was a std plate or wood screw with small head that poped out from the plastic.... ended up in fried ignition this happened 1.5 years after purchase so no warranty. After that Dyna 5 ohms coils and later back to points with Hondaman module.

 Dynatek did also deliver crap with graphite surpresses ign cables, one had intermittent failures that tricked my carb jettings. Thats why I have a few sets of copper cable and extra NGK caps just for sure for future problems. These cables were bought here locally though

[Wingnut74]

For what its worth, I followed up to ask VintageCB750.com about whether they had seen reports of this before - trying to figure if I am going back in my newly buttoned up head and cylinders to get it out. They said they have sold around 500 of these cam tensioners over 6 years with only 1 report of this issue. 

[madmtnmotors]

For what its worth, I followed up to ask VintageCB750.com about whether they had seen reports of this before - trying to figure if I am going back in my newly buttoned up head and cylinders to get it out. They said they have sold around 500 of these cam tensioners over 6 years with only 1 report of this issue. 

Now there's an unbiased source of information. 

I'm in the same situation, but based on PeWe's experience, "letting it ride" is not even an option as far as I'm concerned. Feeling lucky? 

The nature of the failure could very well lead to a broken cam chain, leading most of us poor clueless ba$t&rds to believe the cam chain was to blame. How many guys will tear it down because it did not "feel right" as PeWe did? If you want to wait, I will be posting a review of my Vintage CB750 cam chain tensioner with 1500 miles on it by the end of the week.

I would think that a broken cam chain could result in a seized engine. This could end badly if it happened at highway speed. 

de-Nile ain't just a river in Egypt... 

[Jerry Rxman Griffin aka MuthaF'er]

Broken cam chain or valve into piston.

[Wingnut74]

For what its worth, I followed up to ask VintageCB750.com about whether they had seen reports of this before - trying to figure if I am going back in my newly buttoned up head and cylinders to get it out. They said they have sold around 500 of these cam tensioners over 6 years with only 1 report of this issue. 

Now there's an unbiased source of information. 

I'm in the same situation, but based on PeWe's experience, "letting it ride" is not even an option as far as I'm concerned. Feeling lucky? 

The nature of the failure could very well lead to a broken cam chain, leading most of us poor clueless ba$t&rds to believe the cam chain was to blame. How many guys will tear it down because it did not "feel right" as PeWe did? If you want to wait, I will be posting a review of my Vintage CB750 cam chain tensioner with 1500 miles on it by the end of the week.

I would think that a broken cam chain could result in a seized engine. This could end badly if it happened at highway speed. 

de-Nile ain't just a river in Egypt... 

I was so happy to have gotten this far without incident, and so not looking forward to that cylinder process again, but now you got me thinking.  I will be on hold pending your results! Thanks for sharing the results.

[Artfrombama]

Just ordered their engine seal kit today. Will stay away from their other parts.
Thinking about making a primary tensioner roller from Delrin, how would you think it would hold up?

[grcamna2]

Just ordered their engine seal kit today. Will stay away from their other parts.
Thinking about making a primary tensioner roller from Delrin, how would you think it would hold up?

I have one on a CB350 twin and it's holding up well.

[madmtnmotors]

I was so happy to have gotten this far without incident, and so not looking forward to that cylinder process again, but now you got me thinking.  I will be on hold pending your results! Thanks for sharing the results.

Yep, I know the feeling. I've even been riding mine trouble free for 1500 miles, some of those down the 1/4 mile at a local track, as well as the SGMP in Valdosta back in November. But, for about another $100 and a little more effort, I won't have to worry about whether the tensioner is going to fly apart when it is needed the most. My curiosity has got the best of me at this point anyway, so now I have to open it up just to see for myself.

Stay tuned!

[70CB750]

One more reason to pull the engine out of Red.  I am pretty sure I got new rubber wheels from VintageCB750 or their sister site in USA.

[bwaller]

Just ordered their engine seal kit today. Will stay away from their other parts.
Thinking about making a primary tensioner roller from Delrin, how would you think it would hold up?

I have one on a CB350 twin and it's holding up well.

First off I'm not at all questioning your abilities, but herein lies the problem. How do you know it's holding up well? Maybe you had it apart to check, don't know. On my racebike I had to make a drive chain guide because of the swingarm angle and tried different materials. Delrin lasts one season. Maybe an internal roller with lots of lubrication will survive better, but it's just not easy to check.

[grcamna2]

Just ordered their engine seal kit today. Will stay away from their other parts.
Thinking about making a primary tensioner roller from Delrin, how would you think it would hold up?

I have one on a CB350 twin and it's holding up well.

First off I'm not at all questioning your abilities, but herein lies the problem. How do you know it's holding up well? Maybe you had it apart to check, don't know. On my racebike I had to make a drive chain guide because of the swingarm angle and tried different materials. Delrin lasts one season. Maybe an internal roller with lots of lubrication will survive better, but it's just not easy to check.

I bought a pr. of them from a man who machined them from 'PA6' (isn't that the same thing as Delrin?)and they are white.I've had the engine apart after 5000 miles w/ no appreciable wear.

[madmtnmotors]

Just ordered their engine seal kit today. Will stay away from their other parts.
Thinking about making a primary tensioner roller from Delrin, how would you think it would hold up?

I have one on a CB350 twin and it's holding up well.

First off I'm not at all questioning your abilities, but herein lies the problem. How do you know it's holding up well? Maybe you had it apart to check, don't know. On my racebike I had to make a drive chain guide because of the swingarm angle and tried different materials. Delrin lasts one season. Maybe an internal roller with lots of lubrication will survive better, but it's just not easy to check.

I bought a pr. of them from a man who machined them from 'PA6' (isn't that the same thing as Delrin?)and they are white.I've had the engine apart after 5000 miles w/ no appreciable wear.

Well now we're comparing apples to oranges. The original post in this thread addresses specifically those cam chain tensioners distributed by Vintage CB750. Your custom machined rollers from an as yet undetermined material doesn't really shed any light on the durability of the tensioners sold by Vintage CB750. Those of us that may have fallen victim to substandard materials from Vintage CB750 are facing engine disassembly (or engine failure) just to find out.

[PeWe]

It might be possible to check by unlock the tensioner adjuster (push bar). Mine did not move much out when the tensioner was locked up by the rubber parts. Or remove the entire holder, 3 M6 bolts and somehow look inside, in and upwards to verify the rubber wheel is OK.

The photo with an arrrow marked where the rubber parts were located. The cam chain blocked the rubber to fall the other way, the push bar  an obstacle to fall down. My rubbers were still there after the tensioner holder and push bar was removed.