Jog R, starts but wont rev - almost seems like flooding

Hi All, ive taken this from another post i had running as the issues in that are now sorted and this is alittle more specific of a problem.

had a few issues with my late 2006 jog r i have just bought, fixed most but have one last issue before heading off for MOT - Ever since i bought the bike, it initally started fine and rode ok but half way on the ride home, lost power on hills or whenever the throttle was opened more than 1/3 of the way.

Since getting it home i have done the follow - with the following outcomes:

Changed Spark Plug - No Change (although the HT lead appears to have a sparkplug cap stuck in it and i had to screw the new plug in to it removing electrode from new one)

New Battery (fixed electrical probs, inc button start but no change to riding)

Removed and refitted exhaust (had to get to brakes anway) - when riding the bike with the exhaust loose performance was the same, since putting it back on fully tight with no leaks, new gasket, problem appears worse, engine literally dies within 10 seconds of applying any more than 1/4 throttle.

Removed and cleaned carb fully and checked fuel line for flowing fuel - if anything this didnt help but made it worse, it now starts perfectly but has real problems revving.

Changed the length of throttle pin in carb by moving clip up/down - no change

Fresh tank of gas - no change

Tried altering idle speed, and mixture - after cleaning carb it was idling slightly rough, though changing idle only seems to make a difference when cold, adjusting the mixture just seems to alter how far you can rev it before it dies, and weather if you release throttle if it carrys on running.... almost seems like engine is flooding.

Last symptom is that when you first start the bike, it seems to be ok, within 20 seconds is when the problems get worse as things begin to warm, apparently bike had been sitting without use for few months before i purchased it, and i think it might be highish milage (think 10kish), when i removed carb, someone had disconnected the choke (maybe mistake not to reconnect) - having it connected or not makes no difference.

Any suggests on things to try would be appriciated!

 

you said since refitting the exhaust, with no leaks, the problem appears worse.

maybe your exhaust needs decoking, or is partially blocked somewhere :glare:

you also mention that the running of the engine gets worse as it starts to warm up, this would suggest it is running very rich, could be a problem with the carb/jetting/mixture screw or even a sticking choke. you didnt mention if it was auto choke or manual...

 

Hey, someone else mentioned the exhaust being blocked actually, its something i will look in to although bathing it in caustic is a mission - choke is auto by the way, think i said when i first looked at the carb it was disconnected (power) so wonder if the previous seller had it like that for a reason.... i tried just now losening off the exhaust slightly again to see if it made any diff like before, and it might have been 10% better but no more than that.

 

Auto chokes do fail from time to time, and if you unplug the choke, it means its permanently switched on....the choke switches off as the engine warms and switches back on as it cools,so if you plugged it back in and there was no difference, then theres a chance thats your problem

 

Yep, having the choke connected didnt seem to change much - i assume you can test it with a voltmeter... will try plugging / unplugging it this evening while the bike is warm and idling - then test with a meter if i grab a cheap one somewhere.

Also took some pics of the original / replacement spark plugs to see if they might shed some light on matters - after replacing the plug in the bike having given it a wipe over, it seemed to imrpove it slightly for all of 30 seconds, odd really as its only 2 weeks old and done less than 2 miles... (ticked over a fair bit though)

original


replacement

 

The problem youve got is: you cant do a plug reading by only doing 2 miles.

There are 3 different circuits in your carb, pilot jet/idle mixture...needle...and main jet.

you have to be sure which you are reading.

check the choke out 1st, remember you need to check that not only its receiving electric, but also that the plunger is moving up and down accordingly.

The plunger will rise up to let extra fuel into the engine (cold) and go down to shut the extra fuel off (warm)

 

plug looksa tat rich , but that probly due to dieing out or flooding as ur trying to start it.

My bike did the same didnt die just went really slow once warm.Take the filter off i thought yea like it would be that looked it looked clean , use some good cemical stuff at collage and the difference i would have never thought in a million years.

So clean filter
disscont the auto choke like people said
Rollers arnt worn at all. worth a try and way.

 

Do you mean take off / clean the air filter - if so ive already soaked it in soapy water and given it a good once over, airbox too (if exausht doesnt help i will try running for 5 mins without it).

Just tried looking at the choke, dont have a multimeter at the mo so couldnt test resistance across it / voltage - but i did take it out before starting the bike, took a pic and then put it back , ran the bike for 5 and took another pic, will upload shortly - hard to tell, looks like its moved from the pics though.

I then let everything cool off again, checked the choke one last time to make sure it returned to normal position, and started the bike without the power to choke connected, in honesty it ran loads better for a little while, still didnt have much power but allowed mt to rev it for a short time.

The exhaust is in the garden full of caustic soda at the moment, was quite hard filling it, and the level keeps going down slowly (so im topping up) - either my plug on one end of exhaust is leaking v slowly, or the stuff is slowly working its way down the pipes... i did try with water and found it hard to put water in one end and drain from other so it might have been alittle blocked, will see tomorrow.

 

Well, cleaned out the exhaust in 24 hours of caustic soda, put it back on the bike today, no improvement really - same problem of engine beginning to rev then cutting out.

I also tried losening off the air filter to see if incoming air seemed to affect it which it didnt (maybe made it worse, and the bike louder).

Also tried spraying wd40 on the connection between the carb and the airbox to check for leaks, and a little on the carb to the engine pipe, didnt seem to change anything....

have taken a 30 sec vid of it here, u can see the bike starts perfectly, and idles ok (although its not always like that, sometimes struggles to idle slightly but i think its part of same problem) - if you rev it, the engine just dies off and you have to release throttle (notice bike rpms die well before i release throttle), on the last one i keep the throttle held and the bike just dies, same as always.



Any more help would be greatly appriciated, im all out of ideas and totally noobish with bikes

 

Bump - anything would be helpful... was thinking maybe float needs adjusting in carb perhaps (no idea if that would cause this), maybe coil / ht lead replacement might help???

 

did you check the choke operation ??

 

Yep, in honesty it seemed to run better with the power to the choke disconnected altogether - i took choke out, took a snap, put it in and started the bike, left it 5 mins came back and took the 2nd pic below.

I then disconnected the power the choke, stopped the bike for 20 mins came back and did the same without it powered, seemed to run a little better if anything.

 

Dave, anyoneeeeeeeeeeeeeee Helllllllllp :banghead:

 

ok...lets just recap...

am i correct in thinking the engine starts ok ?

whats happening after that? does it run really rough, or does it run ok on the stand?

 

starts with half a second press of starter, or single kick start - ticks over fairly smooth and idles fine on stand.

If you open throttle, the bike begins to rev - gets 2/3 way up rev range then just dies (u can see the effect in the utube vid 2 posts up) - if you release throttle it goes back to idling slightly more roughly for few secs then normal, if you hold throttle open rpms just keep dying and after couple of seconds it totally stalls.

If you give it 5 seconds, it then starts again fine from starter and idles ok.

:edit: oh should say it seems slightly worse the warmer it gets, and even worse still if u sit on bike off the stand (try to pull away).

 

is the bike totally standard ?

 

as far as im aware, i havent changed anything on it - the jet looked quite small when i cleaned the carb although im not 100% sure by just looking.

standard exhaust

standard airbox

I have just bought a viper sports exhaust just as a test to totally eliminate the exhaust as the problem (it was cheap on ebay and i couldnt be sure that caustic sodaing my old one made it perfect).

But yes, to best of my knowledge its standard, im not even bothered by extra speed, if it did 30 mph it would be an improvement so i could use it to get to station

 

The 1st thing i would do is whip the carb off and check the float needle is moving freely,
the float is seated properly, and hinged properly, and not punctured.

blow through the jets, and whip the inlet manifold off, check it for splits/air leaks and check the reeds while im at it...

 

thanks for your replys, in case anyone has a similar issue its now resolved - took it to a mechanic in the end, he said the throttle needle was out of spec - ordered a new one, put that in and its been running fine ever since.

I wasted a good deal of money on parts only for it to need a 15 quid needle kit