Curvy SV running badly.

Hey all,

My girl picked up a 1999 curvy sv at the weekend and when we drove it home we got aout 10 miles and it was running like a bag of poop, stuttering, backfiring, popping from the exhaust and carbs etc. We pulled over turned the bike off and rang the seller, had a quick chat and he said to bring it back, so we set of back and the bike was running perfectly. We met back up with him and agreed it must have been something passing through the carb so kept the bike. Bike did about 60 miles running fine. Gave the bike a wash and polish.

Started the bike up yesterday and it was crap again, cleared out some water from the front cylinder which didn't fix the issue. Removed and checked the carb jets, bowls etc. Took the bike to my dad and the carbs were out of balance so we balanced them, took the bike home and it felt good, smooth, powerful and no previous symptoms.

Started it again today, same issue occurring. Bike will idle but pops and stutters. Put some new plugs in but it has not sorted things. I have a feeling it's running lean as it seems to get hot very quick but not 100% confident in that diagnosis.

Any ideas?

[andrewsmith]

Clean up the coil and Ht lead and ends cured mine almost.
Check the fuel lines aren't kinked

sent from a weapon of mass distraction

Check the battery is connected properly. Not speaking from experience or anything

I did check the spark against the cylinder head before putting everything back together and I was getting a good spark from both ht leads

[Sid Squid]

Sticking chokes and water in fuel caused by duff filler well piping.

Neither is certain in your case, but both are good reasons for a Curvy to run poorly.

Don't think the chokes are sticking, I had them off yesterday and although the action at the lever isn't perfectly smooth they do seem to return fully.

Water in the fuel is the next step, going to drain the tank and see.

Morning all,

Tought I'd update this as we are making progress but not there yet. Bike is running better following new plugs carb balance and carb cleaning. Yet to drain tank but will get some cans this weekend. My gf rode it Tuesday night and although it was popping on start up and idle apparently it ran like a beauty on the road.

However I votive when we got in the exhaust was properly hot, like untouchable and this was after a 10 -15 minute ride. It's got a standard exhaust, is it normal to get very hot very quickly?

I'm leaning to the bike running too lean and getting hotter than it should.

Can anyone tell me are the mixture screws adjustable on curvy sv's and if so what is the default setting?

Chees

Dean

[mikerj]

There are screws to adjust the two pilot jets, but this is only affects idle and low speed running. Standard setting is around 3 turns out from fully closed IIRC. They are a bit of a pain to get to though and they are prone to seizing.

My dads curvy had similar case of irregular poor running which was caused by something being partialy blocked in one of the carbs causing it to run lean, especially when cold. Several strip downs and thorough cleaning with carb cleaner and compressed air and even soaking the carb body in celly thinners overnight failed to fix it, so eventually we put a good s/h pair of carbs on and it's been perfect ever since.

So this freaking saga continues. Stripped the bike down again and rechecked the carbs, jets etc all fine.

This time my dad and I freed off the pilot screws, and reset them to the factory settings. yes they were seized! One came out easy enough, the other required the Application of heat, wd40 and a Dremel.

So took it out for a 10min spin and it went loooovely.

Set off home a few hours later, and I got 100 yards before the dash lights dimmed, bike appeared to be switching on and off, the rev counter and speedo starting flying about and the bike died at the side of the road. All characteristics of a dead battery.

But why? Anyone else come across this issue? I'm thinking we dislodged a plug when fitting the carbs and airbox, or the battery is toast and that's why it's been misfiring in the first place.

[dirtydog]

Originally Posted by quik_d

So this freaking saga continues. Stripped the bike down again and rechecked the carbs, jets etc all fine.

This time my dad and I freed off the pilot screws, and reset them to the factory settings. yes they were seized! One came out easy enough, the other required the Application of heat, wd40 and a Dremel.

So took it out for a 10min spin and it went loooovely.

Set off home a few hours later, and I got 100 yards before the dash lights dimmed, bike appeared to be switching on and off, the rev counter and speedo starting flying about and the bike died at the side of the road. All characteristics of a dead battery.

But why? Anyone else come across this issue? I'm thinking we dislodged a plug when fitting the carbs and airbox, or the battery is toast and that's why it's been misfiring in the first place.

I had a similar problem which was caused by a loose battery connection. Dash flickering, needles jumping around and running like poop