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World of motorcycleS |
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World of motorcycleS |
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| After removing the ignition system and the 8 head nuts I visualy checked the cams for wear or damage, |
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I covered the camchain tunnel and the reast of the head before grinding off the two pins from the "soft" link. On most engines you can remove the camchain from the sprocket, but not this one, it's designed to be split and a soft link fitted. I ground off the rivet heads (after coveing the rest of the head with a cloth to catch any swarf) |
| I removed the four sleeves and o rings from each outer edge four head bolts |
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Then I removed the two bolts beside the spark plugs |
| And the bolt from between the two inlet rubbers |
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Then removed the camshaft | |||
| The right piston, which was the one smoking was carbonized, obviously in need of a de-coke. The carbon was 2.5mm thick in places (I measured it using the vernier guage) |
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As you can see, the left hemi-sphere is oily as well as being carbonized. The right, is carbonized too, just not as bad. | |||
| Placing the Valve spring compressor |
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When compressed, removing the two collets is easy |
| Then the cap- |
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and the two springs |
| Then the valve it's self, as I pulled the valve I put a finger over the rubber boot from the other side, I got a bit of vacuum as I pulled. this showd me the rubber boots weren't split as well as checking the valve sems for streightness. |
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I then checked the stem, although carbonized, no sign of burning. I noticed some pitting on the valve seat, a good clean up and a re-grind is in order. |
| Before re grinding the valves, I decided to clean the head. Polished it too (when all valves were removed, noting which valves came from each port. |
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I found some pitting on the head seat too. |
| I used fine gringing paste and valve grinding tool, I re-seated the valves. Then I removed all used paste before replacing the valve. I repeated this for all four valves. |
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by using the valve spring compresser as above but in reverse order |
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| The barrels seemed to be near perfect, I could hardly feel any
ridge. No scores to worry about either.
When checked with an internal guage it showed that hardly wear had occored to the bore. No need for re-bore |
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| Piston, one had 2mm of carbonizing on the head, same as the 2mm
found in the head. The other was nearly clean. This I deduced is due to
fuel getting into the combustion chamber, but not exploding. Thereby sleaning
the piston. This could be due to an electrical or carb problem, we'll have
to suss that when the engines back in the frame and running.
There is the possability that the fault has already corrected, but either way, that machine has been running on one or one and a half for a while, even if it was running just before we stripped it. |
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| I removed the piston rings and using normal feeler guages, I
checked the gap. As there was plenty of room between the ends of the rings
I knew that the rings were worn.
Worn rings let oil into the combustion chamber, which burns, smokes causing the carbonizing found the both piston and both hemi-sphere. Confident I had found diagnosed the engine problem, I gave the part list to the owner. |
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Yep, with new rings underneath the old, the width of metal worn os obvious |
| How the gap should look like........ |
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| Cam chain guide. A part most people thing can't werar out. I think this one did after about 27years.There is a very good possability that the camchain tension had been incorrectly adjusted somewhere in it's past. I know that when I removed the tensioner, it was in the correct position. |
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Lower oil filter, blown. Due to blackage. The blockage seems to be worn out ground down plastic, probably from the cam chain guide. | |||
| Cam chain. well will last another year, but I'd replace it if given the chance. | ||||
| Oil feed pipe (I'll explain this another date. | ||||
| Rockers: I noticed (by eys and feel) that the exhaust rocker had had
bad flat spots. These were caused by lack of lubrication and over tightening
of the tappets (no gap at all). The lubrication problem was caused by gasket
sealant or a silical sealant. The four corner studs had worn rubbers under
the head nuts, so they probaly started to leak, I can guess that the person
who last rebuilt this head had just used the sealant to stop the leak.
Either way, the flat spots have now been re-contoured, and should run. When I turned the engine by hand there was no more knocking. If youwant to know how to remove the rockers from this model, click here: rocker_removal |
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| I placed the new base gasket into position, then oiled the small end journals |
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Then oiled the gudgeon pins (as we call them over here in blighty,
wrist pins for the rest)
The origional pistons and pins were re-used |
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| locating the pin into the small end is done mainly by feel with just a bit of the pin in the gap on the underside of the piston. |
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A drift was used to correctly position the pin.... just tapped in gently using the palm of my hand instead of a hammer. | ||
| A rag was strategacly placed inderneath the pistons before inserting the circlips. |
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The new rings | ||
| The ribbed one goes in first |
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into the lower groove | ||
| Followed by one the two thin (scraper) rings, which just underneath |
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The second of the thin rings goes just above. | ||
| The fatter of the compression rings goes into the middle groove, it won't fit into the top groove, so you can't realy get it wrong. |
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and then the top compression ring. I made sure that the gaps do not line up | ||
| I then blocked the pistons up using a wooden block below the piston and above the crank case, keeping the pistons upright and near Top Dead Centre. lower the barrels over them, until they were resting on the top rings. I used two small screwdrivers to push the top rings further into their grooves, making sure they were both just in the barrels, we gave a quick tap on the barrels, using the heel of the palm (gently) until the barrells reached the middle rings, again, a squeeze with the screw drivers and a tap. I didn't have enough time to photopraph these steps. |
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As a replacement for the cam chain guide, the used one was replaced., followed by the head gasket |
| the crank was turned uusing a 17mm spanner to find the TDC mark, and line it up with the mark just to the right of the T in the plate. Sorry if you can't see it in this photo, but at least you can see the T and the mark you need to line it up with. |
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The cam was then placed into the head making sure that the groove (shown just below the new soft link) to the top. The Cam timing done, the soft links were riveted by a special tool (not yet shown here) |
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But I have finished the engine before Christmas 09.
The owners sorting it out in his own time, but I can't wait the hear it roar again. Si 17-14-2010 |
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