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Discussion Starter · #1 ·
Hello all, i'm Ricks son, Joe, and after spending many hours working on his AT trying to get it running right i've still had no luck, so thought id put a post up on here in case anyone had any ideas.
Dad is a fairweather rider, so bike was put away before winter running perfectly. Over a month ago it was awoken from its slumber in the garage. Considering the timeframe it had been standing, it started fairly well. Was running a little rough and lumpy but nothing overly unexpected. Assumed this would smooth out once it had had a ride. It didnt.

First thing tried was a gallon of Shells finest with some redex, after getting over the placebo effect, this was revealed to of made bugger all difference. Bummer. Bike came apart, carbs were removed, stripped and cleaned, before checking over linkages and then being refitted all shiny. Seemed to start better and run a little better but still not right. Bike idles perfectly, low speed is okay, but it has absolutely no grunt, by the time your into third its reluctance to rev is almost comical. Odd thing is that it doesnt cough, splutter, spit, backfire or anything of the sort. It runs smooth as an AT ever will, it just has no power. If Honda had made a 125 Africa Twin this is how it would feel!

Bike was stripped again, carbs were again removed, stripped and cleaned, all good. Both coils were removed and checked, primary and secondary windings all good. HT leads checked, fine. Throttle position sensor also checked, all good. Fuel filter checked and cleaned, all good. Bike was reassembled and all the above was found to of made no bloody difference! Grrr.

Next course of action is to change the plugs just in case, despite only having a new set of Iridiums around 2k ago. But i've had duff plugs in the past so i've not ruled it out. Anyone else got any ideas since i'm about to take the bloody thing apart again for the third time in 2 weeks!

Strange one this, any ideas are much appreciated. Thanks for reading regardless. Bike is an '02 RD07A.

Cheers, Joe.
 

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I would also look at fuel hoses (genuine Honda ones required as mine had a straight bit of hose and this had a kink in that was very detrimental to the bikes operation)
Fuel Pump?
Throttle Cable?

Good luck with it Joe....:thumbright:
 

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What's the air filter condition?

I had something similar where a melted HT lead was shorting on the exhaust but you say you've checked those.
 

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It sounds like partial fuel starvation, i.e. at higher revs when more juice is required. You can check the efficiency of the fuel pump by by-passing it with a piece of tube, but only when the tank's full and the fuel level is thus higher than the level in the float bowls (when no pump assistance is needed).

As for the plugs, I've had duff ones (not on the @ though) which are fine at low speed but fail at mid/high revs which results in severe misfiring....doesn't sound like this from the symptoms you describe but worth a try.
 

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I'd be looking at the state of the carb diaphrams,splits or subtleness of the rubbers.
 

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Doesn't sound like plugs to me either, if it's running that smoothly. If it turns out not to be fuel starvation, I'd say it sounds like either the throttles aren't opening as much as they should, or the slides are sticking. If you can bear to take it the tank off again, I'd suggest you take the airbox connections off the carbs and look into the throats while opening the twistgrip; see if the butterflies open fully. If so, I'd then check that the slides will move freely. Seems odd though that both would be playing up; asking a bit much of coincidence. But worth checking, even if only to narrow it down.

What colour are the plugs? Did you check the main jets when you stripped/cleaned the carbs? It doesn't take much varnish to partially block a jet, and it has been standing a while.

And I suppose you've checked the handbrake...
 

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Discussion Starter · #7 ·
Thanks for all the replies!

Loggy: Fuel hoses have been checked, no issues. Fuel pump is a Facet posi-flow jobby, all working correctly. Throttle cable seems good, TPS reads correctly as throttle is twisted. Cheers for the luck, think im gonna need it!

Chronyx: Air filter is good, HT leads are good. Thanks for your suggestions.

Steingberg: I would agree with you apart from the fact that the bike doesnt bog or stutter or anything similar. Early thought was that the float chambers weren't filling. When (trying to) accelerate, it doesnt feel so much as if theres a restriction, just simply that the bike isnt producing any power. Through first and second its smooth and it will rev fairly high, just no wheelies. Sad times. Theres no misfire, no untowards noises. Amount of throttle applied seems to make little difference to the bikes performance once it hits this 'barrier' if you like. Thanks for the suggestion though, and as you mentioned ill be changing the plugs anyway as there such an easy (not) job to do!

Are the CDIs prone to issues? Anyway of testing these?

Thanks again, Joe.
 

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Discussion Starter · #8 ·
Grasmere: Cheers for the suggestion, ill be having a look when i remove the tank. Diaphragms common issues on these then?

Tim: Again thanks again for the suggestion, different angle and although it'd be a heck of a coincidence, stranger things have happened! Stupidly didn't remove old plugs last time it was apart. Will report plug colour when i've taken the poxy thing apart again. Main jets were checked, and all seemed to be flowing through very well, but they'll be checked again with the tank off.
As for the handbrake.... Rookie error, wheres the release again?

Cheers, Joe.
 

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I had diaphram problems on a car years ago,it was after a lay up.It would start and tickover etc,no misfires but wouldn't pull the skin off a rice pudding out on the road,long shot but worth a look.
 
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As others have mentioned. It sounds like fuel. Is the fuel filter clear?
 

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What are the carb-to-head rubbers like? If they're perished, or not fitting properly, mixture will be weak, particularly at speed.
 

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It sounds like either fuel or air starvation unless the brakes are severely binding.... sticky slides sounds plausible if unlikely, surely you'd give them a feel when you had them off? - how long has the bike beel laid up?
Do the ATs have an in tank filter?
Have you measured the fuel flow through the pump?
I feel an air leak would make the bike run poorly at tickover & low revs with much less affect at higher revs.
 

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Looking at some of the replies and I would check the internal's of the exhaust haven't collapsed over the lay-off. Not happened to me on a bike but once had a
MKII escort that had power problems, which kept me guessing for some time, until I checked the output from the exhaust pipe and found it producing virtually nothing.
'New exhaust system and full power restored'. "Just a thought".
 

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hi rickmercs,
I'd be looking at the state of the carb diaphrams,splits or subtleness of the rubbers.
i think it's exactly that. had the same problems last week. no power above 4000u/min. at idle it ran almost perfectly. now i heard from my mechanics that the carb membran from the front cylinder is broken.
chears from austria
 

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Definitely looks like a lack of fuel.

I suppose that the fuel tank is totally full, and that gravity itself is enough to bring all the fuel the carbs need. Was the bike stored with the full fuel tank? If not, it is possible some rust has formed and has clogged the jets or fuel passages. I suppose you have checked the carbs' diaphragms.

My suggestion as a next step is to borrow a set of good working carbs and try them. If the problem is not solved, then you know it comes from somewhere else. If it is solved, then you know the problem comes from the carbs. At least it will help you get closer to the source of the annoyance...

Lee
 

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Tell your Dad to send that bike back to me, I will ride it all year round and then there won't be a problem :D
 

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Discussion Starter · #18 ·
Big thanks for all the replies guys, some interesting theories that are most definitely worth checking out. Carb diaphragms are sounding unfortunately likely.

Bob: Get in line! I've already offered to do the same! :D

Stay tuned, im off to take it apart, again.

Cheers, Joe.
 

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Discussion Starter · #19 ·
Carburettor diaphragms are good and intact, and have provided much amusement whilst trying to get them back in place. Slides and butterflys are most definitely free and in sync.
Carb rubbers are good, both carb to head and airbox rubbers.

Part of me was hoping to find a split diaphragm, the other part is glad i didn't as ive read there getting tricky to source?

Any other ideas whilst its all apart?

Cheers, Joe.
 
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