Starts Slow

[Jimbenge]

I have a 1985 K-100 sidecar rig with nearly 200K on it and it has been acting a little funny for about a year now.  When I start it, it runs real slow and needs a minute or two to warm up to run on all 4 (I guess) after it warms up a bit it runs fine.  I have not checked the valves or compression yet, it seems like it might possibly be plugged injectors, but it runs pretty good when warmed up.  Anybody got any idea what is going on here before I start taking everything apart ?

Thanks in advance..........

[frankenduck]

Where I'd start:

At 200k I'd get the FIs recon'd as general maintenance.

And check the valves.

[ReneZ]

What's the maintenance history? I would go back to basics; valve clearance check, compression check, air leak check, FI service, check fuel pressure, synchronise TB's and whilst you're at it clean all the electrical connectors.

[grant71]

hi. add valve ease to your petrol before you start all the expensive stuff. helped me. good luck Grant

[argent brick]

What is "valve ease" and where do you get it? Never heard of it before.

[frankenduck]

What is "valve ease" and where do you get it? Never heard of it before.

Fuel system cleaner with some graphite in it.

At 200k I'd get the FIs cleaned merely as general maintenance.

[Jimbenge]

Today I checked the compression, 140 lbs each cylinder, I did not check valve clearances, but with even compression I am pretty sure they are OK.  I set the idle speed up to 950 RPMs, it was very low (500 RPMs) either the screw came loose or wore down ? (a bitch to set on a RT),  and put new spark plugs in (old ones were gaped at about  40, new ones gapped at 25.  Now it starts much better but still needs a little warm up.  Not sure what it will do once really warmed up (may have to reset the RPMs again).  I will be going to the Brass Monkey sidecar rally next month (about 300 miles each way) so I will run some Techron fuel additive both ways and see if that helps.  Part of the problem may be this cold weather and I haven't run the rig much this year.  I really don't want to pull the injectors just yet as I will be using the bike.  If this dosen't work well I can send off a set of spare injectors that I have for rebuild/cleaning, that way I won't be waiting on anything once I go in there.  Thanks for the replies, I will report back after the Brass Monkey sidecar rally.

[grant71]

here in South Africa valve ease is available from Wm. Penn and Valvoline. older mechanics swear by it. as well as my  86 K100 I also have a 76 Mercedes 230 automatic 6 cylinder which is in superb condition. i use valve ease in the Merc as well. apparenly valve ease helps by decarboning the valves. a small bottle serves 75 litres of petrol.

[Jimbenge]

OK, the verdict is in.  We went to the Brass Monkey Sidecar Rally in Lake Havasu Arizona and did a side trip to Oatman (an old Ghost Town turned tourist trap) while we were there.  Did about 730 miles all together pulling a 6oo pound trailer behind the rig.  As planned I used a heavy dose of Chevron Techron on every tank coming and going.  The rig did seem a little under powered the 1st tank full and I got crappy gas mileage, but we were going up hill and bucking about a 4o MPH wind.  The bike ran fine non the less.  The rest of the trip the bike ran great.  The Bike started fine every time.  When I got home I let the Bike set for about a week before trying to start it again.  Starts right up and runs as it should.  So the Techron must have worked.  Now I am wondering if I should even bother with pulling the injectors or not as it seems to run fine.

[TimTyler]

Today I checked the compression, 140 lbs each cylinder, I did not check valve clearances, but with even compression I am pretty sure they are OK.

I'm not a mechanic but... A compression check tests the valves when they're closed, right, not their position when they're supposed to be fully open?

If your valves are tighter than spec you'll have performance problems.

I put almost 10,000 miles on my bike before finally discovering the exhaust valves were super-tight. Adjusted them to spec and afterwords the bike felt like it had a fresh engine. Big improvement.