what the actual fuk

[Varastorm]

Chin up matey, we'll fix it

[jchesshyre]

Just wrote this on the fb forum as well but, going back to the point at which this started - swapping the tank:

I've been thinking through the (not very many) parts that get touched when the tank comes off. The shrouded electrical bundle containing the fuel light connector has more connectors in than I realised, including the following ones which would definitely cause running problems if they were dodgy and this dodginess got worsened if they were disturbed when you disconnected the fuel light connector:
– Alternator connector
– Side stand switch connector
– Rear ignition coil connector

Worth checking these for damage etc.?

[freeridenick]

I think your main jet air bleed on the original carbs would have been blocked to prevent a lean running condition. My guess now is that one or both are now open and that's screwed your fuelling. Stock carbs would run sh1t too which would be why they made no difference.

Mine was horrible on a part throttle until these bleeds were blocked.

[fabiostar]

main jet airbleed ? that has me a little stumped have to say

[jchesshyre]

I think your main jet air bleed on the original carbs would have been blocked to prevent a lean running condition. My guess now is that one or both are now open and that's screwed your fuelling. Stock carbs would run sh1t too which would be why they made no difference.

Mine was horrible on a part throttle until these bleeds were blocked.

Why would the problem have only started when he changed the fuel tank though?

[KermitLeFrog]

"Never underestimate the power of coincidence"

With all the things changed it sounds to me to be electrical. Or, something in the valve train?

How long would it take to swap the engine into the yellow one?

[Stephan]

I think your main jet air bleed on the original carbs would have been blocked to prevent a lean running condition. My guess now is that one or both are now open and that's screwed your fuelling. Stock carbs would run sh1t too which would be why they made no difference.

Mine was horrible on a part throttle until these bleeds were blocked.

same for me, but only for lidless airbox configuration

[8541Hawk]

Plugging the air bleed was an HRC thing to do when running ram air.
I can run through all of it but I doubt it is an issue in this case.

Like I stated in the other thread, it sounds like the fuel system has been gone trough quite thoroughly.
So at this point I would run through the ignition system starting with testing the pulse generator.

[fabiostar]

an engine swap i just dont have the energy for anymore Ian..... id be afraid of ending up with two buckets.

in all this changing of carbs and coils,ecu,plugs airboxes,fuel lines ,tps units,rec unit x 3. nothing has made any difference , not a jot until the yellow bikes carbs went onto it then it run worse? yet the blue carbs run fine on the yellow bike.

i started blaming the tank change thinking id sucked dirt in but i no longer believe the tank has anything to do with it, and the fact iv tried 3 different tanks and the carbs, all 3 sets are spotless.

cam timing checked.
valve clearences checked
compression checked. 176 front 174 rear both done dry
no oil burning
no rattles or bangs

but a really slow starter if i go anywere near the choke, infact it wont start on choke at all.. the choke can only be used when the engines warm and riding in the midrange.

iv never seen an engine do this sh1t before..


on the plus side, the yellow bikes pulling great wheelies

[Stephan]

I have the same behaviour with choke, but it started since day 1 after rebuilt, so I thought it is due to higher compression. Other than that, bike is running fine.

Have you checked movement of buterflies when turning the throttle?

[fabiostar]

I have the same behaviour with choke, but it started since day 1 after rebuilt, so I thought it is due to higher compression. Other than that, bike is running fine.

Have you checked movement of buterflies when turning the throttle?

everything seems fine on the butterflies on all the carbs iv used. its threw me a bit when i put the blues bike carbs and lines onto the yellow bike and its running great .

[fabiostar]

ok strange got stranger..... it wouldnt start with the yellows bikes carbs on for more than a few seconds then refused to start. while looking for a box of matches to burn it with, i shouted at it, pointed my finger and squirted some easystart into it and it fired.. it then ticked over?

so i thought why not. bolted the tank down(the new tank id made up) went for a spin and after about two miles it cleared it throat and .for some reason its flying why? who knows, its good at the bottom,its good at the top end and with constant throttle its fine.. if i was picky id say maybe just not as sharp on pickup coming back on to the throttle but youd have to look for it to notice it...

i have no idea why this has happened or whats sorted it.... i only done about ten miles so il wait to i get a better run but going on the last week id say its 99% better than it was..


for my sanity thank god almighty,, and the yellow one is still running with the blue bikes carbs, im not going near either of them unless they play funny buggers again..

i hope, THE END.. cheers for the advice lads

[freeridenick]

iv never seen an engine do this sh1t before..

This is why I think it's the air bleeds. From what you describe it sounds similar to my bike after the engine and airbox work. Wide open it was fine but on a part throttle it felt sluggish. It turned out it was very lean. And that was with the airbox lid on. The first thing Andy did was block the main air bleeds and it ran way better. We sorted the main jets and needles then did the same with the open airbox. From memory all it took was going up a couple of sizes on the mains with the lid off.

Here's what my logic says happens with a stg1+ engine. Big cams, big valves, porting etc mean it sucks way more air so it runs rich - more air sucks more fuel. On WOT that's easy, just drop the main jet sizes. I run 165/168 front rear. With the lid on they were 155/158, I think.

Without cutting the carbs open I think the air bleeds draw air from the airbox down and out through the hole in the carb throat while the air passing the butterfly pulls fuel from the float bowl through the jets and out the same hole. With WOT the vacuum created in the carb throat pulls enough fuel in to deliver the right mixture but on a part throttle it can't so the air through the bleed leans the mixture out. Block that and the air passing the butterfly is the only air in the mix. This is only a problem when a Storm is able to suck a lot of air. And I'm pretty sure it's why Tony couldn't get the MWR filter to work, which I'm running happily.

The pic below is of the front carb from the front of the bike looking back. Middle tube is the main bleed, right is the pilot and the left is the enrichment circuit. Or maybe the other way round, I can't remember. If you look closely you can see the middle hole is sealed.

Check your carbs Fabio and if one is blocked and the other isn't that's your issue. If both are open I think that's your issue too but you would have had to misplace something otherwise it wouldn't have run so well beforehand. If they're both blocked I'm stumped.

[fabiostar]

aaah i see said the blind man... mine arnt blocked and never have been since owning it... also my jetting since getting this engine with its matching carbs is so different to yours like miles different. im running 48 pilots and 190 mains front and back and its always been super clean tho i run an airbox lid and gutted box inside..


but tonight as i said above, with the yellow bikes carbs and blue bike jetting it ran like sh1t and stopped,, then wouldnt start, tonight when i used easystart it fired and for some unknown reason other than the gods know its going again?

id say atm and its early days as iv only done ten miles or so id say its 99% cured. maybe the very odd fluff when rolling slowly back onto the pilots but so slight you have to hunt it out.... fingers crossed it keeps acting like this.

the yellow bike with its own jetting in the blue bikes carbs is running the very best.... how,why? who can tell..

[8541Hawk]

Without cutting the carbs open I think the air bleeds draw air from the airbox down and out through the hole in the carb throat while the air passing the butterfly pulls fuel from the float bowl through the jets and out the same hole. With WOT the vacuum created in the carb throat pulls enough fuel in to deliver the right mixture but on a part throttle it can't so the air through the bleed leans the mixture out. Block that and the air passing the butterfly is the only air in the mix. This is only a problem when a Storm is able to suck a lot of air. And I'm pretty sure it's why Tony couldn't get the MWR filter to work, which I'm running happily.

Actually the bleeds sit above the emulsion tubes and their purpose is to add air to the fuel being pulled through the main jet.
It does this because the "emulsified" fuel is easier to pull through the jet.

The old example of this was "think of drinking through a straw. A carbonated beverage is easier to suck through the straw than a non-carbonated beverage."
This is also why you go down on the jet sizes when you plug the bleeds. you are now drawing straight fuel not an air\fuel mix through the main jet.