1990 Force 90 Timing/Carb Synchronization

[Force_90]

I recently bought a basket case 1990 Force 90, and rebuilt the power head myself (my first time, but I think I got it right). Cylinders now have good compression. It starts and idles, but it does not do well when I start getting up in RPM. Smokes profusely and sputters. I have played with the timing and linkage but nothing seems to work. It is winter now, so I can't put it under load. I have adjusted full open timing with a light, as described in the manual, but still no good. Could I have a crankcase seal leak (I did not change any seals when I did the pistons)?

 

[Mod2]

Re: 1990 Force 90 Timing/Carb Synchronization

Moving to Chrysler/Force Repair Forum.

 

[Force_90]

Re: 1990 Force 90 Timing/Carb Synchronization

Here's a few more tidbits: When starting cold, the motor backfires violently out the exhaust once or twice. Also, there is a lot of oil coming out of the snout. I only know this because I turned it over a few times without cooling water hooked up to check the timing, and I noticed a small puddle of oil under the snout. I have totally cleaned all carbs and they are good to go. Any suggestions on how to troubleshoot to narrow the problem?? Thanks very much in advance.

 

[seldont]

Re: 1990 Force 90 Timing/Carb Synchronization

Firstly not meaning to offend, I would not start it without the benefit of having water running to the engine or at the very least you will be replacing the impeller which may not be a bad idea anyway. If you have a leaking crankcase seal it should probably should be repaired as the fuel mix is pressurized in the crankcase. A bad seal affects the amount of pressure you have as well as the amount of air within the crankcase and can lead to a lean condition. Did you inspect your reeds while you had the motor apart?? And is your timing correct at idle. I have not had the problem of backfiring out the exhaust before. That sounds like the timing is retarded at low speeds. could beother things as well. There are many knowledgeable folks here and I am sure someone will lead you the right direction.

 

[Force_90]

Re: 1990 Force 90 Timing/Carb Synchronization

Thanks for the reply. You will not offend me, this is the first time I've attempted a major repair on an outboard, so I'll take all the help I can get. I planned on getting the engine running well before I spend a lot of effort on the lower unit, so my plan was to just keep an eye on the water temp and flow coming out, which seems to be fine for now. I will replace the water pump eventually. I did inspect the reeds, they looked brand new, no crud whatsoever. Would a bad crankcase seal cause the excess oil coming out of the exhaust snout? I have adjusted the timing as described in the Clymer manual. Once it backfires a few times, it idles fine. My real problem is once I start giving it gas, it starts to run very rough and spews smoke. Does a good-running motor sputter and smoke when run at mid to high throttle with just a hose hooked up? I know it needs to be under load to really adjust wide-open timing, but I can't believe just putting it under load will make this motor run well. Spark plugs after running it look okay, slightly wet with grayish liquid. Thanks again!

 

[seldont]

Re: 1990 Force 90 Timing/Carb Synchronization

In my experience two stroke outboards never run smoothly hooked up on muffs. At least not as smoothly as they do in the water. They need the backpressure on the exhaust and the water pump to smooth them out somewhat. I have a Force 120 and if you rev it and hold it in the 3000 rpm range it sounds as it is running rough as well. Runs great in the water. They always sound somewhat rough kinda like a chainsaw at idle or just above. Inherent to the two stroke design I think. As for the oil out of the exhaust snout all of mine did that as well. It is the water washing the dirty exhaust out and it is pretty normal unless it is excessive which would indicate an overly rich mixture.

 

[seldont]

Re: 1990 Force 90 Timing/Carb Synchronization

By the way when you cleaned the carbs did you use new gaskets?? needles and seats?? Did you adjust the float settings after you cleaned them?? Just something to think about.

 

[Franki]

Re: 1990 Force 90 Timing/Carb Synchronization

Since this is a 2 stroke we are talking about..<br /><br />There is no crankcase full of oil.. the only oil (apart from the grearcase) is the oil you put in the fuel...<br /><br />Having said that.. my question is.. what fuel/oil are you putting in???<br /><br />If your running under 50:1 mixture and your running in a barrel at low revs for extended periods.. I'd be very surprised if allot of oil wasn't comming out the exhaust..<br /><br />It does sound abit to me like a timing issue though.. (the backfiring and spluttering, not the smoke and oil)<br /><br />rgds<br /><br />Franki

 

[Force_90]

Re: 1990 Force 90 Timing/Carb Synchronization

Thank you for your replies. These may seem like obvious things you've both pointed out, but to me they are very helpful. On the carb questions: Yes, I replaced the gaskets, but not the needles and seats. Everything was so clean that I didn't think I needed to. On the fuel/oil question, I am running 50:1. From both of your comments, it sounds like before I get carried away, the smartest thing to do may be to wait for some open water in the spring to test it out and adjust the timing. Patience was never one of my better traits.... Thank you both very much for taking the time to help me out!!!

 

[seldont]

Re: 1990 Force 90 Timing/Carb Synchronization

Hopefully you will get everything ironed out okay and seems like you are on the way. Although they may not have the best rep the Force engines are very simple and easy to work on. Good engines for the compulsive tinkerer with the exception that parts are getting harder to find.