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Message |
    
phil
New member
Username: phil
Post Number: 1
Registered: 07-2004
| | Posted on Friday, July 23, 2004 - 08:11 am: | 
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I am new to the group so G`Day to all.
I have a P55 MAD that misses badly on the rear cylinder , i have checked compression , changed plugs ,leads , carby , coil ,cleaned the points etc.
All to no avail i must be missing something.
Also the dyna start drives off the flywheel , yet the older manual states that the Dyno should not exceed about 3350 R.P.M.
Any advice or help would be greatly appreciated.
Phil. |
jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 204
Registered: 07-2002
| | Posted on Saturday, July 24, 2004 - 06:52 am: |
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Welcome to the site Phil, I'm not familiar with your particular engine but will offer some general advice. It would help to know if it's missing at idle, high speed or both. Check to be sure you're getting fire to the plug, the cap could be carbon tracked, points too close or wide along with a worn distributor. Look at the valves to make sure they are all moving the same, worn cam lobe? Check valve spring tension. |
phil
New member
Username: phil
Post Number: 2
Registered: 07-2004
| | Posted on Saturday, July 24, 2004 - 10:00 am: |
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Thanks jb. Its a Stuart Turner 2 stroke.No distributor cap as such, two sets of points off the one cam , leads straight to 2 sperate coils, one for each cylinder.I think i have swapped everything around on each cylinder but keep getting the same result.an occassional firing on the rear pot. there is spark at the points of both cylinders and i put a timing light in the rear plug lead it seems to flash consistintly as the motor is running ....just not firing on that rear pot all the time. |
jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 205
Registered: 07-2002
| | Posted on Saturday, July 24, 2004 - 08:31 pm: |
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Phil, that's not what I pictured. Mark your flywheel 180 degrees apart, be sure the cylinders are firing opposite, adjust the points to correct if necessary, you can hear when the buzz coils fire. If you have even compression on both cylinders, check your inlet valves, poppet or reed,be sure they're seating and free, or is it a three port? Three ports are sensitive to piston to cylinder clearance, wear or scoring. Crankshaft bearings are important, a leak will kill a cylinder, usually worse at idle, any other case leak as well. We have a smoke generator at the shop for checking vacuum leaks, works well for this. Maybe your local garage has one. Exhaust ports coked up will kill a cylinder, this will usually start affecting high speed first and when bad enough will start showing up at idle. |
jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 206
Registered: 07-2002
| | Posted on Sunday, July 25, 2004 - 10:23 am: |
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One more thing, with one carb and two cylinders the problem could be on the cylinder that's firing. You will adjust the carb to satisfy the lean cylinder and it will run fine for a while, then it will flood the good cylinder. If the missing cylinder turns up with a wet plug, look at the other one. |
peterogborne
Senior Member
Username: peterogborne
Post Number: 195
Registered: 09-2002
| | Posted on Monday, July 26, 2004 - 08:31 am: |
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Phil .....for a start your Dyna start should not be driven from the flywheel rim. There is a spigot on the hub and a six inch pulley is attached here .
Some models have a chain driven dyna start with a clutch ,from you description your is the belt driven model . Get that pulley on the flywheel spigot and you wont overspeed the dynamo.
Inconsistant running on the rear cylinder.........It sounds electrical ,but check the clearance of the centre crankshaft bush . This is a rotary valve and directs the charge to the two crankcases. The clearance should not be more that .008''. With mine i run a bit of white metal and bore it out again.
Also throw away your plugs and get some new ones . Spark plugs can be a real bastard sometimes and can cause you so much angst . For the price get get some replacements
Give us some details of the contact breakers . |
phil
New member
Username: phil
Post Number: 3
Registered: 07-2004
| | Posted on Tuesday, July 27, 2004 - 08:25 am: |
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Thanks jb , Peter, for your input.I have removed all the ignition system wiring and am putting new wires in to coil points key etc, removed points ,backing plate and cleaned it all again . Will put it back together tomorrow and see what happens. plus new plugs.This motor still has the manual start/crank on it, i think the dyno may have been a home installation, does`nt appear to have been a pulley anywhere on the front, though it would make the revs about right.
There are two sets of points running off a cam where the magneto would normaly be ,points are set to 013 Thou. points timing can be altered individually.
Both crankcases appear to have equal pressure /suction when motor cranked over.
So we will see tomorrow.............. |
phil
Member
Username: phil
Post Number: 4
Registered: 07-2004
| | Posted on Wednesday, July 28, 2004 - 08:35 am: |
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What happened?Well it has made a fair improvement by redoing all the wiring and soldering all the connecters.Still missing occasionally on the rear cyl. What i have now found after much starting and then checking everything about 10 times is that there is always some liquid fuel in the rear crankcase after running the motor.The motor will start and run on either cylinder .It appears that the motor draws a charge of fuel into each crank but is not delivering it to the rear cylinder properly.100% on the front and 85% on the back .Everything else seems pretty even pressure ,suction,spark etc.I have blown air through all the system.
Could it be that bearing that you mentioned Peter ?
I looked inside the expasion chamber and no stuck rings or any obvious signs of anything.
Is it possible that the motor can be too rich on only one cylinder ?
I will check back later , thanks for your time. Phil.... |
peterogborne
Senior Member
Username: peterogborne
Post Number: 198
Registered: 09-2002
| | Posted on Thursday, July 29, 2004 - 06:49 am: |
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Phil.....could be the centre bearing but it could also be the crankshaft seal . There are two.If they are the originals ,they are a bronze seal ,ok when they are new but they do wear. It means pulling down the engine but it is simple enough . Fit new seals ,the synthetic rubber ones . They are easy to fit cost only a couple of dollars and last a long time. Just take your crankshaft OD and the ID of the crankshaft housing to your local bearing supply and they will have them . |
peterogborne
Senior Member
Username: peterogborne
Post Number: 199
Registered: 09-2002
| | Posted on Thursday, July 29, 2004 - 06:54 am: |
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Phil ...I forgot to mention the following . It is most unlikely but have a look at your pistons . The crowns have a deflector and they must be in the right way otherwise the charge goes straight out the exhaust port . As i say it is most unlikely but you never know!!! |
phil
Member
Username: phil
Post Number: 5
Registered: 07-2004
| | Posted on Thursday, July 29, 2004 - 08:52 am: |
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O.K. Well it looks like i have to strip it down to find the little problem. I was hoping to have it running nice and sweet before i stripped it down for cleaning and painting , as i was assured it was in good running order.???
I am going to put a magneto on it and remove the dyno system , which the more i look the more im sure was a home add on.Anyhow thats the plan.
Well at least i know what i will be doing for the next few days. Re the pistons i checked them when i had the cover off the expansion chamber and both seem to be facing the correct way.All will be revealed by the w/e.Will let you know what i find. Thanks Phil..... |
graham
New member
Username: graham
Post Number: 1
Registered: 07-2004
| | Posted on Thursday, July 29, 2004 - 08:31 pm: |
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hi mate i have a p55 fuel mix an plug try can let me no pls what to use |
phil
Member
Username: phil
Post Number: 6
Registered: 07-2004
| | Posted on Monday, August 02, 2004 - 06:55 am: |
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Well back again, have removed the head , that took care of the w/e very stubborn little sod it was .Cylinders off today.
After removing the cylinder block ,i could see there was a cavity above the centre bearing containing a small quantity of fuel mix.
Is this the problem you were talking about re sloppy bearing allowing fuel to not be properly delivered to each cylinder, Peter ?
It would certainly explain the way it was running.
Will try getting it out and measured this week.
Thanks Phil......... |
peterogborne
Senior Member
Username: peterogborne
Post Number: 200
Registered: 09-2002
| | Posted on Monday, August 02, 2004 - 08:52 am: |
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Phil, there should not be any fuel gathering in the spaces you mention. Lets see what sort of clearance you have on that centre bush. If it is excessive you can as i mentioned before run some white metal [babbit] on to it and rebore it |
phil
Member
Username: phil
Post Number: 7
Registered: 07-2004
| | Posted on Wednesday, August 04, 2004 - 09:12 am: |
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Motor is now completely stripped, i had the shaft and bush measured today. across the bush 002 thou clearance top to bottom 006 thou.
Neoprene seals are fitted appear o.k. but i will replace them, bearings good no movement.
? when these motors are assembled is there any kind of sealer that is applied to (a) where the bush /rotary valve fits or (b)where the crankcase housing ends fit.
It seems like a small amount of sealer has been used , looks like dried shellac only black.
Regarding the fuel mixture , mainly oil i mentioned in the cavity above the centre bush, i can find no way for it to have gotten there tested the locating pin with penetrene and no seepage.Head gasket was destroyed in removing the head so learnt nothing from there. Phil... |
phil
Member
Username: phil
Post Number: 8
Registered: 07-2004
| | Posted on Thursday, December 23, 2004 - 12:40 am: |
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Well its taken a couple of days but motor is now back together ,after stripping ,soaking and painting.( I did resurrect a little Penguin in the mean time.)It seems to run better so i will put the problem down to a leaky rear seal as that is all i could really find, just needs a bit of fine tuning on the carby side of things now.
So i`m now looking for another project.
Merry Christmas to all and have a safe holiday season...Phil.. |
phil
Member
Username: phil
Post Number: 9
Registered: 07-2004
| | Posted on Thursday, December 23, 2004 - 12:52 am: |
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I forgot to mention re the dynamo, i got in touch with the Stuart Turner people in the U.K.and there was a model that had the dyno running by belt from the outside of the flywheel the motor was built for D&J.Fowlers in 1968.....Phil.... |
