’89 XLH1200 Single?

[cyclobutch]

I've had an ongoing problem with my bike this last couple of years in that one of the cylinders seems a bit lazy, for instance being late to chime in when starting on the choke. Last year that had got bad enough that it had a tendency to drop onto one whenever the revs fell – all a bit awkward for in town riding, especially when that second cylinder chimed back in again. So I'd put it to one side (I have other bikes to ride).

Finally got around to looking at it the other week. First up was a compression test. I know this is supposed to be with an open throttle, so I pulled off the air cleaner and then clamped up the slide (CV carb) to do this. In psi I got 165 on the rear and 155 on the front. I'm not sure on the spec for this engine – it's an original 1200 that has never been broken down, but they are at least within 10% of each other. So I figure that is OK.

The bike was fitted with a CV carb with no accel pump, a peculiarity from around that time I think, so all OE. I'd taken the opportunity to buy a later one with the pump (from an '04) so then fitted that. Firing up on the driveway (after standing for maybe around 6 months) it still seemed a bit one sided until it warmed through. I have the bike on SORN (it's a UK thing – 'Statutory Off Road Notice'; for those too stingy to pay road tax in the winter months) until the end of the month so can't road test until April but I'm not hopeful.

I guess the next trick will be to look at the ign. The plugs both looked good when I pulled them, and I replaced the coils and leads only a couple of years ago so don't really expect any issues in that area.

Anyone got any insights on where I should be looking next? Thanks. 

[aswracing]

In stock form, it's dual-fire. So one thing you could try is switching the spark plug wires front to rear, and see if the issue follows. That would tell you if it's electrical or not. Also do the same trick with the spark plugs.

Also, the no-accelerator-pump CV was 1988 only. In 1989 they got the pump.

[cyclobutch]

Thanks - I'm not even sure which cyl drops but that sounds like a plan. I've noticed that the date stamps on various components on this bike are marked up as '88 so that makes sense. I guess it took a long time getting here on the boat, or sat in a showroom for a while before getting registered.

[Panzer]

Let us know what happens when you do as suggested.

[cyclobutch]

Yep, sure. It'll be a couple of weeks now before I can look at it again, and as noted - April before I'll run it up the highway anyway.

[King Inky]

Hey cyclobutch,

Have you gotten around to checking this out? By the sound of it, I believe I had a similar problem. My suggestion is to check your spark plugs and see if they are the same color or if one happens to be carbon fouling or if one is turning white due to a lean condition. If that is the case, it is most likely a bad intake seal (not terrible to replace if you have ball-end allen wrenches).

Keep us posted and hopefully you can get it solved to get out and ride!

[Panzer]

Try changing plugs too...... to the specified ones it calls for.

[Panzer]

AMAZING............NEEDS HELP AND NEVER A FEED BACK AS ASKED..............BUTT HEAD. 

[cyclobutch]

Oi – be nice. I've not had time to pull the old gal out from under cover. I've been needlessly replacing a whole load of ignition components in a Sunbeam (a wretched machine to be sure), trying to make a Morini brake a little better (now there's a Vee twin with all the character of a rattly Honda single), and re-fork the Bantam 'pie crust racer' after my last get off.

I do appreciate any input here, and will report on findings once I'm back under way with it. I did pull the plugs when I made that compression test – they looked pretty much spot on.

And thanks for your continued patience – I will get back to this.     

[cyclobutch]

Just a quick update. I decided to bite the bullet and plumped for a new coil, leads (with caps) and plugs. I found the time to put the bike up on the table and fit those yesterday. Bike fired up on the driveway OK, but runs snotty on the choke – and needs it for a while so I've no view of the overall effect at this point. Being in the dying days of another month I wasn't going to stump up for road tax (complete months only) just to take a test ride. Should be doing this next weekend.

On removal the rear plug was a good deal blacker than the front, but given my last run out was only local to the MOT station I think this is probably not indicative. One other note on those – I see that HD brand plugs are recommended; Really? That's what came this time and I've fitted. The plugs I took out were NGKs.

[cyclobutch]

So I got the old gal all legal and out on the road at the weekend. Only for a brief ride mind – to the local shops. So never really got off the choke (enricher) properly, and I suspect I have made the classic mistake of fooling with too many things at once ... new carb and new coil. Somewhere out there the bike got real arsey, spitty and farty. A quick check showed that the HT leads were at least properly plugged in both ends. It's bad enough I'll not be using it for the daily commute out to the railway station this week. I'll look to take it for a longer run at the weekend and then go looking for air leaks I guess.   

[cyclobutch]

A final update on this one. I ran the bike out a little further at the weekend and with the same serious popping and banging going on. Back at home and up on the table I swapped the carb back over. Out on the road, all of that issue was cleared again, and the original problem – that of the lazy cylinder seems to be pretty much cleared.

So the problem appears to have lain in the coil, leads area – as suggested here. Many thanks.

Though it's kind of good and bad – the coil I took off is really no age at all. I fitted that myself only a couple of years and a few thousand miles ago.
Of the carb problem I now have I'll start a new thread.