Would a pre-filter help in that case?
Help Support VMAX Forum:
Would a pre-filter help in that case?
Not being a thermodynamics engineer or A & P license-holder, I can't speak with authority or first-hand knowledge about the carb icing. Seem to me that in cases of extreme humidity and low temperatures, coupled with low barometric pressures, you get the carb-icing phenomenon. That's why some carbs used hot-water-jacket circulation from the cooling system and had 'heat manifolds' coming-off the exhaust manifolds, to prevent such manifestations of air-borne moisture sublimating into bellmouth ice. I recall I had more than one Weber-carbureted auto which had those heating features, all snow-belt cars. Don't aeromotive carbs have electric icing control?
OK. this is it!! I am at a total loss...The bike ran great, went out tonight and its cold but not wet. I got to the sports bar to watch the Rangers play and everything went awesome on the way there. However on the way home, at 6000 RPM I was pushing 45mph WTF!!! I tucked in and at 6500rpm I got to a whopping 50mph, Im no physics major and certainly not a mechanical engineer but unless my clutch is toast I should have gotten up to a little faster speed maybe Im wrong. But when my bike was dialed in and I took it up to 4000 rpm anb dumped the clutch I got the from wheel off the ground. Help guys I am loosing the battle here.
dannymax
Well-Known Member
Sounding more like clutch issues.....I regularly ride in the 50's and never have icing issues. Never heard of anyone else in the NE having those problems either....not impossible, mind you, but seems like this would be the region for it to occur.
You can test the clutch by placing the front tire against a building and dumping the clutch....but I'm not sure of the gear or rpm's to use tho.
You can test the clutch by placing the front tire against a building and dumping the clutch....but I'm not sure of the gear or rpm's to use tho.
ninjaneer
Well-Known Member
can a clutch problem be sporadic? meaning sometimes the symptoms show? i would think that it would be more consistent, like cat would notice it all the time. i guess it could also depend on driving habit/style. i mean, it's only a couple data points, but cat seems to only encounter his problem on the way home...
{daydream}
hmmm...you know...and this is totally of topic, but whenever i took my dog out for a walk, he'd be jumpin for joy, but as soon as we started heading home, the dog would refuse to continue and pull on the leash and get all lethargic. hmmm....
{/daydream}
perhaps because cat's bike is mushy at 6K he has a v-boost prob? maybe the airbox boot(s) or the intake manifold mount(s) is/are leaking? maybe the v-boost servo? maybe the butterflies? **shrug** i surely could be tossing out nonsensical ideas, but perhaps the gesture will spark more logical suggestions.
{daydream}
hmmm...you know...and this is totally of topic, but whenever i took my dog out for a walk, he'd be jumpin for joy, but as soon as we started heading home, the dog would refuse to continue and pull on the leash and get all lethargic. hmmm....
{/daydream}
perhaps because cat's bike is mushy at 6K he has a v-boost prob? maybe the airbox boot(s) or the intake manifold mount(s) is/are leaking? maybe the v-boost servo? maybe the butterflies? **shrug** i surely could be tossing out nonsensical ideas, but perhaps the gesture will spark more logical suggestions.
johnpclynch
Well-Known Member
What gear were you in doing 50 @ 6500rpm? When you open the throttle do the revs rise with the speed or do they jump up and fall back to meet the speed (sounding like an old automatic)
Check the heat of your exhausts when you're having troubles, you could be misfiring on one or two cylinders - turning your Vmax into an FZX
It may be worth adding a fuel additive like Seafoam, I use Silkolene PRO FST which absorbs moisture in the fuel system and helps prevent carb icing
dannymax
Well-Known Member
Hmmm, my Korean pot bellied pig was just the opposite, going out in the woods for a walk she would drag behind, I'd have to wait for her to catch up....grumbling every step of the way! But on the way back to the barn....and feed trough (I might add)....she was a regular fat little Greyhound!!......Go figure!! :ummm:
I was in 3rd gear when I got it up to 50mph, With the throttle WFO the revs never rose or fell. Pull the clutch in and the revs go up like normal so Im stumped there. I just did the "shotgun" service couple of days ago and there was no problem after that but I didnt ride at night again until last night.
Ninjaneer said something about the clutch, It was new at 40K miles I have 49600 on the bike now. But it grabs and runs great during the day when the temp is up. The oil is fresh 300 miles ago. The air filter is new K&N I checked the servos when we did the "Shotgun" and they seem to be fine. Maybe my bike is afraid of the dark and doesnt like the cold?? I added Seafoam to the gas as a preventative caution the other day. The plugs are new as are the boots.
I had a bike blow a head gasket on me riding over the Rocky Mountains in Arizona once. The power disappeared and the bike would get over 35-50mph BUT the was oil EVERYWHERE my bike runs like it has no compression on any of the cylinders. But when we tested it all four had 120+-
Maybe a leak-down test to see if it's intake (air hiss @ carbs) or exhaust (air hiss @ muffler tip), or rings (air hiss @ crankcase oil filler) is needed.
It almost sounds like a bad CDI box or wire for the ignition function. An infrared thermometer from Harbor Freight will painlessly inform you of a dropped cylinder, quickly & easily. I think that's what I would try first, see if one or more of the cylinders isn't firing next time it shows the symptoms.
It almost sounds like a bad CDI box or wire for the ignition function. An infrared thermometer from Harbor Freight will painlessly inform you of a dropped cylinder, quickly & easily. I think that's what I would try first, see if one or more of the cylinders isn't firing next time it shows the symptoms.
A weak/bad CDI or coil would be an easier explanation to swallow than the other points that have been made throughout the post. The electrical would explain the sporadic behavior. I mean if it were a compression issue it would be constant right? Also if it were a clutch problem it would be constant as well.:ummm:
johnpclynch
Well-Known Member
Could it be a problem with fuel delivery? it's Ok when the carbs full but the pump can't deliver enough while you're driving down the road?
I had this when I developed a pinhole in my cheap fuel filter. The pump was sucking more air than fuel, a corroded fuel line will do the same
I had this when I developed a pinhole in my cheap fuel filter. The pump was sucking more air than fuel, a corroded fuel line will do the same
"Replace with one of good known operating quality"
The gauge of the connectors from the plug for the wiring harness into the CDI circuit board are really-thin,and if one or more of those broke, that could be your problem.
"CaptainKyle" and Sean Morley probably have them (CDI's). Or, if you could switch-out with someone w/the same series CDI, by you...
The gauge of the connectors from the plug for the wiring harness into the CDI circuit board are really-thin,and if one or more of those broke, that could be your problem.
"CaptainKyle" and Sean Morley probably have them (CDI's). Or, if you could switch-out with someone w/the same series CDI, by you...
dannymax
Well-Known Member
Think I'm mis-interpreting this, is the motor revving at WFO but the bike's not picking up speed, or is it bogging down at WFO and not making power, resulting in it not picking up speed?
Not picking up speed, not bogging down but not responsive at WFO either. I put it on the lift today and found out what it is doing, but have yet to isolate the cause. It is running on 1 cylinder. BUT its sporadic. Sometimes all four then only 1 and the one is also a variable like it changes which cylinder its hitting on:confused2::confused2::confused2:
Well that sure sounds like a spark problem, I think you need to get a digital infrared thermometer so you can find-out which cyl's drop & when. Have you tried to run the fuel pump into a container to see how-long it runs & what volume it produces in a given time?
Seems to me it would be extremely obvious when it was running on only one cyl as it would barely move and who can't recognize the sound of a 1 cyl vs. a 4 cyl.? Keep looking.
Seems to me it would be extremely obvious when it was running on only one cyl as it would barely move and who can't recognize the sound of a 1 cyl vs. a 4 cyl.? Keep looking.
We ran the pump to drain the fuel out and check flow, found no issues there. We used the thermometer ( I picked one up the other day when you suggested that) Thats how we found the weird firing and running on various cylinders. It is very obvious that it is running on one cylinder but again it is sporadic and the other night it was running fine then power drop..We are going to break it down further today and try to get the electronics sorted out. Any tips on CDI diagnosis??
dannymax
Well-Known Member
Have you checked it in the dark for spark jump?
Do you have COP's?
Do you have COP's?
We checked for spark jump or any voltage signal and it is sporadic. I made the decision to break it down and go completely through it. During this Im going to do the other up grade mods that were suggested in the other post. Also it will get a new paint job, and the wheel set polished (still going to wait til the new rubber is worn before widening the rear wheel.)
OK, this is what we have found so far...
The coils under the seat loose spark sporadically
The fuel filter needs to be replaced
I think the fuel pump is jumping in and out due to a power loss/bad connection
The plug in the rear right cylinder is white
The valve cover bolt O-rings on the rear cylinder leak
There is a tick/tap noise in the rear cylinder head.
I am thinking it is time for an overhaul right??
The coils under the seat loose spark sporadically
The fuel filter needs to be replaced
I think the fuel pump is jumping in and out due to a power loss/bad connection
The plug in the rear right cylinder is white
The valve cover bolt O-rings on the rear cylinder leak
There is a tick/tap noise in the rear cylinder head.
I am thinking it is time for an overhaul right??
sdt354
Well-Known Member
Great time to doa cops conversion. The biggest advantage is the ease of changing a coil. Wait till you try to get the left fron out. I left mine in. Check the threads, it's worth doing. Better starts too.
The right rear cylinder? Possible bad rubber boots. If $ tight I can give ya one. I just found my vboost rubbers split and changed them all.Some were ok. Commpression test first of course. I use butane gas from my mini torch to test leaky boots. Spray the gas around the boot, if the engine rpm and sound changes, it's a leak drawing in the gas. Propane is fine too. Be careful, it's a fire hazard Bro.
These engines are loud, but it might be worth pulling the valve covers for inspection.Valves get tighter as they wear on overhead cam engines, but might as well check valve clearance (don't think it's the noise prob). New gaskets are pricey but worth it. I stick them on with Yamabond or any high temp sealer.
To overhaul these engines is super $. They last a long time though. I'd buy a low milage engine if I needed an overhaul. Unless $ is no object, then I'd have at it with Morley, Kyle, PCW. The 1300 venture convertion is super interesting. Most pulling 130 hp or better at the wheel. That's the one I want to do.
Steve-o
The right rear cylinder? Possible bad rubber boots. If $ tight I can give ya one. I just found my vboost rubbers split and changed them all.Some were ok. Commpression test first of course. I use butane gas from my mini torch to test leaky boots. Spray the gas around the boot, if the engine rpm and sound changes, it's a leak drawing in the gas. Propane is fine too. Be careful, it's a fire hazard Bro.
These engines are loud, but it might be worth pulling the valve covers for inspection.Valves get tighter as they wear on overhead cam engines, but might as well check valve clearance (don't think it's the noise prob). New gaskets are pricey but worth it. I stick them on with Yamabond or any high temp sealer.
To overhaul these engines is super $. They last a long time though. I'd buy a low milage engine if I needed an overhaul. Unless $ is no object, then I'd have at it with Morley, Kyle, PCW. The 1300 venture convertion is super interesting. Most pulling 130 hp or better at the wheel. That's the one I want to do.
Steve-o
Similar threads
