Getting 1985 started

[wildlifewestben]

I bought a 1999 which runs great. The seller threw in a 1985 as an extra parts bike which is a great looking machine. I installed a battery and the engine turns over but is very slow and acts as if the battery is about dead (which it is not). What is the possible problem or is the motor shot and not worth messing with. I have some mechanical knowledge but tearing apart motors is not my thing. Just looking for thoughts as to how much effort I put into this bike.

 

[Fire-medic]

Two ways to check the compression: a leak-down test and a compression test. The compression test would tell you about the compression, the sealing of the valves and the piston rings. The leak-down test can express as a % what sealing the engine has.

A cheap cellphone borescope can enter the sparkplug holes where you can see the piston head and the cyl walls. If you find one cyl is leaky, air sounds from the intake side say, 'valves' while air sounds from the exhaust say, 'rings.'

Then you can see about the teardown.

 

[Radioguylogs]

Electrical connections might need cleaning? Starter motor is tired?

 

[MaxMidnight]

First question, how do you know the battery is good and not failing under load?
Start with the basics first - stupid would be a grossly inadequate description if, having dismantled the engine, you find an issue with the battery.
Make sure the battery performs well on the '99 then, as Mr Radioguylogs suggests, start with cleaning all the power leads between the battery and starter and add the earth points in for good measure. Checking the starter brushes and commutator would also be prudent.
If it isn't electrical or starter related then it could be that the motor is tight. Remove the plugs and put it in gear and see how easy it is to turn over via the rear wheel. Provided you can ground all of the plugs (easier said than done) you could also do this with the starter.

 

[one2dmax]

Lot of things you can check but don't overlook the simple fact that many of the early 85-89 starters sucked and were notorious from slow cranking (especially when hot).

 

[wildlifewestben]

First question, how do you know the battery is good and not failing under load?
Start with the basics first - stupid would be a grossly inadequate description if, having dismantled the engine, you find an issue with the battery.
Make sure the battery performs well on the '99 then, as Mr Radioguylogs suggests, start with cleaning all the power leads between the battery and starter and add the earth points in for good measure. Checking the starter brushes and commutator would also be prudent.
If it isn't electrical or starter related then it could be that the motor is tight. Remove the plugs and put it in gear and see how easy it is to turn over via the rear wheel. Provided you can ground all of the plugs (easier said than done) you could also do this with the starter.

Battery is brand new and works fine in the 1999.

 

[sparky4123]

I had an ‘89 and an ‘02 and there is a huge difference in the speed the starter motors crank the engine. The ‘89 needed he battery to be in really good shape to even get it going when cold.

 

[wayne billings]

I gotta question. If all else fails in regards to the starter work. Will the newer 3 brush starter motor bolt up and work? thanks for the info.

 

[Fire-medic]

4-brush? Yes, many people are happy they switched. However, if there is something else going on other than the starter, in its operation, those issues need to be fixed as-well. Having good connections for the electrics is one, as has been mentioned in the past.

 

[MaxMidnight]

It is usually hot starts where the two brush motor gives issues.
Before condemning the starter you need to make sure that the basics are right e.g. that all the electrical connections are in good order.
I have attached some info on checking the starter and a fix for hot start problems which may help.

 

[wayne billings]

Thank you all for the feed back this year. Looking forward to '04, cheers.

 

[MrMAX1985]

I did the hot start fix but I made a ground stud thru case instead of a cable on my 85. Have not had any issues since in the last 2 years. The main issue is using "spring fingers" for a ground circuit.

 

[gavicool]

..good upgrade!!..do you have any picture?..

It is usually hot starts where the two brush motor gives issues.
Before condemning the starter you need to make sure that the basics are right e.g. that all the electrical connections are in good order.
I have attached some info on checking the starter and a fix for hot start problems which may help

 

[MaxMidnight]

..good upgrade!!..do you have any picture?..

Not something I have needed to do myself so the only information I have is what's on the PDF's.