Hard Starting?

[Summit670]

Ok, I've got a wierd issue. 1987 with 74,000 miles and I've owned since new.

I think this is carb related but see what you think.

Bike is hard to start, even just after it has been ridden 20 miles.  Sometimes get a backfire when trying to start it.

When it is running, it idles great, runs great, plenty of top end.

I had previously had a backfire issue and hard starting so I pulled the carbs, installed new orings, needles, float bowl orings, pilot orings/washers, and adjusted the float levels and double checked with hose.  Bike ran fine for a few months after that and now it is acting up again.

Fresh fuel, full tank, valves have a few thousand miles before adjustment needed, installed new pickup coils last year.  Tried a different ICU box I had as a spare. New Yuasu battery 2 years ago.  Stic coils 2 years ago.

Yesterday for the heck of it I drained all the float bowls.  The bike was cold, hadn't been ridden for 2-3 weeks.  I put the petcock on prime for 10 seconds, then choked it and it started up pretty quick and I was surprised.  Rode the bike 20 miles.  Parked in driveway.  front end was up a few inches higher than rear because of driveway slope.  The bike had been shut off for a few minutes then I tried to start and it was hard to start again but no backfire.

[Jet86]

I had that problem to, bike ran fine when riding but hard to start and backfiring even when warm, i could not figure it out til one day i said well a new set of spark plugs cant hurt even if it don't fix the problem but guess what, problem solved.

at least for me it solved it but you might have a different problem but i would take a chance and throw in new plugs, Don't waste time cleaning plugs just throw in a new set, mine looked good but something was wrong with at least one of them.

[George R. Young]

A quick check that doesn't cost anything: the resistance cap-to-cap (1 - 4, 2 - 3) should be around 22 K ohms, approx. 12 K ohms primary and 5 K ohms each cap. Infinite is too high and means there's corrosion at ignition the wire ends.

[Summit670]

Does cap-cap resistance apply when the Stic Coils are used?

[RFH87_Connie]

My '87 tank looks fine inside - does yours?  It sounds like you did a good job on the carbs but maybe stuff got in them again.  I'm not a fan of a fuel filter on this bike.  I'm assuming you are not running a fuel filter but maybe you should look at the sock filter inside the tank attached to the petcock.  Some riders have noted that older ones warp and let unfilter fuel in along the warp.

Don't do the above until you verify there is no water in your fuel.  As many others will attest to, dump the fuel into the car (all of it) and add some fresh fuel and Dri-gas then ride it out.  Drain the carbs before refilling too.  If it was me, i'd drain it all and let it dry out over night with a fan blowing across the open cap - or - (follow safety guidelines) I've also cleaned the shop-vac out (remove the filter) and reversed the hose so it blows nice warm air into the tank to dry it fast.  Mix up about 3 gallons of fuel in a known clean plastic jug, then take it for a spin.  Otherwise maybe the carbs are coming off again.

P.S. - It might just be you have a little gas in a bowl or two that just needs to be drained out.

[Summit670]

I lined the tank with POR 15 many years ago, and the lining still looks good.  When I drained carbs the other day no sediment came out.  When I cleaned the carbs they were pretty clean to begin with (thought it was a carb problem 2 years ago but ended up being the pickup coils had a loose wire).  I clear any potential water out of tank on regular basis.  I'm sure the problem I'm having is not water or quality of fuel because I've gone thru many tanks of fuel and drained any water.

Removed fuel filter a few months ago when I had carbs off.

Like I said, bike started pretty normal when it was cold and had sat for 3 weeks (I drained the bowls just before trying to start it). 

Is there a timing adjustment that can be done to these bikes?  I've never had the timing checked.