1994 Force 90 SportJet Timing

[tjachimiak]

I have a 94 Regal Rush with this Force 90 in it. Oddly, it has the RED stator. I guess someone replaced it. When I got it, it did run smooth on all cyl,for a day or so, but recently things have changed. I have only had the boat for a little over a week. It is smoking with the smell of unburned gas and doesn't have the power that it should. Compression is 135psi in all 3 cyl. The #1 cyl has spark, but when I remove the plug wire with the engine running, there is no change to RPM. Tell me about timing? How should I adjust it on this engine and do I use a regular car timing light? Is it 32 degrees for this engine? I feel that the smoke is coming from the #1 cly that is firing at the wrong time. The plug wires are properly connected in the 1-2-3 order. I put in those $10/ea plugs that have the Z in the model that is supposed to filter out noise hoping that it would do better. It does sound like a timing issue and with your help, maybe I will be out on the lake sooner than later. I have run a tank of all new gas with 50:1 mix and a bit of carb cleaner with little result. It sucks up lots of gas right now. Thanks for your timing instructions. See it at http://tjachimiak.home.mindspring.com/Rush

 

[kenimpzoom]

Re: 1994 Force 90 SportJet Timing

You can use a regular car timing light on it. In fact I reccomend you check for spark with the timing light while running down the river. Check for spark on all three cylinders.<br /><br />For more info and troubleshooting check out my homepage (icon up above).<br /><br />Ken

 

[tjachimiak]

Re: 1994 Force 90 SportJet Timing

Thanks, Ken! I guess yours is the same. I have a nice blue spark on all three cyl. The RPMs drop when I remove either the 2nd or 3rd plug wire, but not the 1st. The 1st is getting great spark. I didn't buy a manual since I am trying to sell her already for a Sea-Doo. I can see the timing linkage, but don't know how to adjust it to the right spec. Can you shed some light on it for me?

 

[tjachimiak]

Re: 1994 Force 90 SportJet Timing

I found this post... I don't know if this was your reply or not, but would this hold true for the 1994 90hp Force?<br /><br />According to the 85 manual there should be timing marks on the Force flywheels. The 85 manual says that older engines may have only two markings, one at TDC and one at 32 degrees BTDC, the right most mark is TDC. The manual notes that to set the timing at 30 or 28 degrees you must scribe new timing marks at a point 5/32 of an inch right of the 32 degree mark for 30 degrees BTDC and another 5/32 of an inch right of that for the 28 degree BTDC mark. If you find several scratches and or marks and can't be sure which are the timing marks this may help. remove the spark plugs, insert a rod straight in the number 1 cylinder and slowly rotate the engine by hand to avoid breaking the rod, at some point the rod stops moving out and stays there as you continue to rotate, this point is very close to TDC, see which flywheel mark lines up with the timing mark on the block. The timing marks are separated by 5/16 inch apart for each 4 degrees, since you are looking for the TDC and 32 degree marks the distance bewteeen them will be 32 divided by 4=8, or 8 times 5/16", this is 40/16 or 2.5 inches. Hope this isn't too much information and that it actually helps. Ken

 

[kenimpzoom]

Re: 1994 Force 90 SportJet Timing

First, even though your spark plugs are new, I would switch the #1 plug to another cylinder to make sure that plug is good. New plugs can be bad.<br /><br />Second, if the #2 and 3 cylinders are getting spark at the correct time, it is highly unlikely #1 is out of time. The only reason I could think of is that the trigger is bad, or the flywheel magnets are bad.<br /><br />You check timing by the marks on the flywheel lineing up with the split in the case in the very front of the engine. Make sure all the plug wires are grounded. Open the throttle all the way. Crank engine. I think it was 36 degrees with throttle all the way open. I'll check in my manual when I get a chance.<br /><br />Ken

 

[funpilot]

Re: 1994 Force 90 SportJet Timing

Here is how I do it... from the clymer manual... It takes two people... not enough hands. LOL. (But if you have a chance, check out Ken's website. You can click on the Kenimpzoom name next to his post for the link. Excellent advice is there for a SportJet owner.)<br /><br />Assure that the zero mark on the flywheel is aligned when #1 is at TDC.<br /><br />Remove the spark plugs and ground the spark plug leads.<br /><br />Connect the timing light to the #1 spark plug lead.<br /><br />Disconnect the throttle cable at the engine, and move the throttle tower shaft by hand to the WOT position. (this will advance the timing linkage and open the throttle plates)<br /><br />Crank the engine on the starter and note the timing marks on the flywheel rim.<br /><br />Timing should be 32degrees.<br /><br />If not, loosen the timeing link locknut and turn the adjusting screw.<br /><br />OR<br /><br />You can tie up to a dock in plenty of water, run the engine at WOT.<br /><br />Check the timing with the timing light, it should be at 30 degrees. The difference from the other test is due to the charactoristics of the CD ignition system.<br /><br />With all due respect to Ken, He recommended using a timing light to check the SPARK at each cylinder, not the timing while running down river. In this case, you are just seeing if you have a steady strobe on each spark plug lead... And you can do that while underway and facing forward if you have a long enough lead on your timing light. I'd be afraid of hitting a wave, loosing the cover (unless I removed it first) or falling into the running engine while peering at the timing marks. So I wanted to clarify that part of his post.

 

[tjachimiak]

Re: 1994 Force 90 SportJet Timing

Many thanks to you, both. I will try your way since I will be alone throughout the procedure. So, the TRIGGER can make only one cyl go out of whack? I was reading Ken's site and got a lot out of it. Thank you for making that Ken. I will let you both know what happens this weekend.<br /><br />Todd Jachimiak, Greensboro, NC

 

[kenimpzoom]

Re: 1994 Force 90 SportJet Timing

Fun pilot thanks for clearing that up. No way you can check timing while going down the river. Way too risky.<br /><br />Good luck Todd.<br /><br />Ken

 

[funpilot]

Re: 1994 Force 90 SportJet Timing

You're welcome Ken!<br /><br />By the way, I discovered something interesting checking the WOT timing on my 120hp SportJet this weekend (tied to a big tree on the bank, with TWO lines to the stearn rings)... after setting the timing at 30BTDC, I discovered my idle timing was about 4BTDC, not the 8-10 recommended at idle... and then it occured to me, the big screw low on the tower linkage isn't a throttle stop screw like the Clymer manual says... it is a low idle timing screw! After bringing the idle timing up, I had to change the length of the connecting rod between the tower linkage and the belcrank for the carb throttle. Which of course meant I had to readjust the eccentric on the belcrank which actuates the throttles.<br /><br />I think I finally get it! The idles speed comes from the 'at rest' location of the throttle butterflies, and the timing comes from the position of the timing shaft when the throttles are completely closed.