Cafe Racer Forum banner

241 - 260 of 265 Posts

·
Registered
Joined
·
5,527 Posts
How about a vintage burnt toast and tested one:


Nope, still not seeing any war between the skirt and the cylinder.
... that covers all the pistons I ride.
 

·
Registered
Joined
·
128 Posts
Discussion Starter #243
So, I've done the following checks here..

-plastigage on main bearings shows some life left. It was at .05mm on all three journals, manual says they are toast at .08mm

- plastigage on Conrod bearings showed even less wear than the mains

- micrometer shows ID on replacement rocker arms is good, they are now in the original cam blocks

- micrometer on replacement cam shows some wear (all lobes at 34.8mm) but no damage and WAY less wear than my other one (some were 34.5....). Not perfect unfortunately. I found a new one not the guy wants 400 bucks for the damn thing. Sellers market...

- ordered the gasket kit and assembly lube so it will be in next week.

Most of the parts on this old shitbox engine are worn out. It won't pay me to put all new components in it, cuz the fuckin thing will cost thousands. The worn used parts may not last too long, which is shit. But I guess I can buy a used engine if I have to later. At this point the cost is in buying parts, and the used ones i have are as good as it gets outside of OEM new ones.

Now to put it back together and not fuck anything up.
 

·
Registered
Joined
·
1,543 Posts
Any 400/450 of that era will fit, you should be able to find a good engine for a couple hundred bucks. It may take a bit of time to find but they made thousands. You did a nice job putting it together and with the change in your thinking from your first post, I'm with Trials...onward and upward. If vintage bikes have become as ridiculously priced in Germany as North America then you should do alright with yours polished up and running. I can't help but think that in Europe, with the variety available, there has got to be some real deals on interesting motorcycles.
 

·
Registered
Joined
·
128 Posts
Discussion Starter #247
Updates...
Mounted the new tacho.
Got my parts in and am nearly finished putting the engine back together.

Should be able to fire it up this week.

Fingers crossed the gremlin is gone
 

·
Registered
Joined
·
128 Posts
Discussion Starter #250
I replaced the cam chain guide, reinstalled all the components and shes a runner! A few things have gone down since I put it back on the road, so here is the update;

1. Ticking noise is gone but not forgotten. It still has the same old tick tick tick from time to time when the bike isn't warm yet. I think at this point, I can confirm that its a combination of things. A) the smaller camshaft for the euro models makes the geometry of the lifter/cam contact more abrupt. B) The parts on this engine are worn. Camshaft is worn a bit, I confirmed the bearings for pretty much every journal have some wear, which likely contributes to lower oil pressure in the top end at start up and while it's cold. Once its warm, It runs very smoothly. I've had it up to 6th gear 5500rpm and on the BAHN at about 100km/hr. Very smooth ride!

2. On my first ride after installing the engine the damn rear wheel broke! Comstars have a small retaining lip on the outside of the chain side hub, and that lip broke off completely. A circlip holds a washer and the drive sprocket on the wheel by pinching up against the lip. I went bobbing down a cobblestone road by my house and next thing I know, the fucking sprocket is flopping around on my wheel. Luckily, I was about 10 minutes from my house and only going about 5km/hr. So I bought some used comstars and this set has had no problem. I can't figure out why the old ones broke... Chain tension was to spec, the sprockets were aligned...

3. Ran out of gas last night for the first time and had to make the walk of shame to the gas station. Luckily in Berlin there's gas stations everywhere so it wasnt a very long walk. Turns out walking these Honda Twins isnt too bad either.

More rookie mistakes to come I'm sure.
 

·
Registered
Joined
·
5,527 Posts
... smaller camshaft for the euro models makes the geometry of the lifter/cam contact more abrupt. ...
The purpose of the valve clearance adjustment is to accommodate thermal expansion. If your clearance is set correctly, there is virtually no clearance once the motor reaches operating temperature. Any other time the valve springs are compressed and it really don't care what your cam ramp is shaped like.


That rear wheel problem. <- Either your chain was out of align or the rubber in your cushion drive hub is shot. There would not normally be sufficient side loads on the chain to cause that breakage unless the rear sprocket is trying to rotate in the completely wrong direction.
One other possibility is the chain was too tight <- do that and something is going to break somewhere for sure and it won't be the chain.

Increased clearances on pressure bearings causing low oil pressure everywhere. Yes that one is a big problem.
 

·
Registered
Joined
·
2,107 Posts
The purpose of the valve clearance adjustment is to accommodate thermal expansion. If your clearance is set correctly, there is virtually no clearance once the motor reaches operating temperature. Any other time the valve springs are compressed and it really don't care what your cam ramp is shaped like..
You might want to do some reading up on that subject. How do you account for engines where valve clearance increases with heat. Not all engines are the same in that department. If the cam and rocker shafts run in aluminum then clearance can increase with heat. Also applies to some push rod engines. I have one where you set lash at zero (cold) just so you can just turn the push rod with your fingers. Because....on that engine clearance increases when hot. Have a look at the CB400 head/rocker assembly. How is it laid out and what is it made of?

Several other things to consider, like time for the valve to dissipate heat to the seat, valve timing, etc.
 

·
Registered
Joined
·
5,527 Posts
.... How do you account for engines where valve clearance increases with heat. Not all engines are the same in that department. If the cam and rocker shafts run in aluminum then clearance can increase with heat...
Lets take one bizarre concept at a time, show me how these valves stems are going to shrink with heat.

Look at your valve clearance and you will see the exhaust needs more clearance, because burning gas is hotter then intake air. Forget clouding the issue with pushrod engines his is a simple 3 valve Honda on one cam. Cam ramp angle makes zero difference to the clearance setting.
As for the clearance on your cam shaft spinning on aluminum it doesn't (we hope) it runs on a microscopic thin layer of pressurized oil, or we have a problem Houston. You can't go making the clearances different because your cam shaft is flopping around in the bearing, it won't work long like that if at all. He doesn't even have roller rocker arms or roller bearing on the camshaft in addition to the oil pressure like oh say, my 3 Honda motors have, and this is the fella that has to replace the rocker arms if not the entire cylinder head already, correct?

 

·
Registered
Joined
·
2,107 Posts
Lets take one bizarre concept at a time, show me how these valves stems are going to shrink with heat.

Look at your valve clearance and you will see the exhaust needs more clearance, because burning gas is hotter then intake air. Forget clouding the issue with pushrod engines his is a simple 3 valve Honda on one cam. Cam ramp angle makes zero difference to the clearance setting.
As for the clearance on your cam shaft spinning on aluminum it doesn't (we hope) it runs on a microscopic thin layer of pressurized oil, or we have a problem Houston. You can't go making the clearances different because your cam shaft is flopping around in the bearing, it won't work long like that if at all. He doesn't even have roller rocker arms or roller bearing on the camshaft in addition to the oil pressure like oh say, my 3 Honda motors have, and this is the fella that has to replace the rocker arms if not the entire cylinder head already, correct?

Ok forget my pushrod engine... it was just an example of an engine where valve clearance increases with heat... didn’t think it was that bizarre. How do you arrive at “there is virtually no clearance when the engine reaches operating temperature”? Yes the valve stems expand... so does the head of the valve and more importantly in this situation.... what about the aluminum cylinder head? I not referring to clearance between the cam and the journals in the head. If the rocker assembly is made from sintered iron or something similar instead of aluminum, then the effect would be less. Think about the relationship between the cam and the rocker shaft..... not just the valve stem. What about the distance between the valve seat and the spring seat... does it remain constant in an aluminum head? To be honest I don’t know exactly what his valve clearance will do when hot... I do know it won’t drop to virtually zero. Are there not other SOHC Honda engines out there where clearance increases with heat? Personally I wouldn’t make an assumption about that engine. If I really needed to know, I would set it cold and recheck it hot.
 

·
Registered
Joined
·
2,937 Posts
Now that "we" have solved the problem, what exactly was the question that was being addressed? Just askin' for a friend. :rolleyes:
 

·
Registered
Joined
·
128 Posts
Discussion Starter #256
Now that "we" have solved the problem, what exactly was the question that was being addressed? Just askin' for a friend. :rolleyes:
I think the question I'm asking myself is why did I take the damn engine apart in the first place???

Replacement parts (new ones) cost more than the bike itself. lesson learned.
 

·
Registered
Joined
·
1,530 Posts
I think the question I'm asking myself is why did I take the damn engine apart in the first place???

Replacement parts (new ones) cost more than the bike itself. lesson learned.

Unfortunately, that is a question that is addressed in the “read first” thread in the New Member’s section. Specifically in post #3.
https://www.caferacer.net/forum/new-members-read-here/22280-read-first.html

You aren’t the first to realize how expensive it gets, real quick.
 

·
Registered
Joined
·
5,527 Posts
Jake, we keep telling people they are sinking so much money and effort into fixing these old cheaply built, abused and worn out motors it would make better economic sense to buy a new motorcycle :/ but most respond with it being a learning experience they seem to need to experience first hand.


Cyorg, you are talking nonsense, i
f you have a way of measuring valve clearance on a Honda overhead valve engine while it is still at operating temperature, please share with us how that can be done.

re: “there is virtually no clearance when the engine reaches operating temperature” <- Because the valve has elongated due to heat to a point where the valve clearance you previously set at room temperature, is all but gone! As in, close to zero excess backlash between the mating parts as possible, without actually making the valves leak.

re: "
Are there not other SOHC Honda engines out there where clearance increases with heat? No! because then it would not be a valve clearance adjustment, that would make it a pre-tension adjustment.


 

·
Registered
Joined
·
128 Posts
Discussion Starter #259
Jake, we keep telling people they are sinking so much money and effort into fixing these old cheaply built, abused and worn out motors it would make better economic sense to buy a new motorcycle 😕 but most respond with it being a learning experience they seem to need to experience first hand.


I heard that haha
 

·
Registered
Joined
·
2,107 Posts
TrialsRider; Cyorg said:
f you have a way of measuring valve clearance on a Honda overhead valve engine while it is still at operating temperature, please share with us how that can be done.

re: “there is virtually no clearance when the engine reaches operating temperature” <- Because the valve has elongated due to heat to a point where the valve clearance you previously set at room temperature, is all but gone! As in, close to zero excess backlash between the mating parts as possible, without actually making the valves leak.

re: "
Are there not other SOHC Honda engines out there where clearance increases with heat? No! because then it would not be a valve clearance adjustment, that would make it a pre-tension adjustment.


I think I get it... you’re just trolling. Right?
 
241 - 260 of 265 Posts
Top