Engine problems

[why walk]

I have just had to have my bike restricted to 33bhp, it was at 42. the problem is that whenever i hot 60mph it develops a misfire, and won't pull any more.
has anyone else ever had this problem? and if so how did you fix it?
Also is it normal for these bikes to find a 'spare' neautral between 5th and 6th? mine seems to completely disengage between the top two gears, i have to hit the gear lever twice to frind 6th.

 

[drewpy]

how was it restricted? @ 42 bhp I assume it was a dohc model? 38hp was SOHC standard!

there can be a false neutral between 5th and 6th, just got to learn the bike.

 

[why walk]

nope, its a sohc, with dunstall cans on it. but I'm still sceptical of the readings the guy gave me.
He put spacers on top of the needles, to stop the rising up very far, so I don't think its possible to sort the problem out, as its simply not getting enough fuel through when the throttle is wider, I have had a little poke around since I got it done, runs like a dream if take the restriction stuff out looks like I just gotta deal with it being slow for now.
Just really sucks cos it means I'm topping out at 60 and 55 uphill.
Oh well

 

[OliverB]

Wow, sure glad we don't have those restrictions on bikes here! Only ones that would apply to here are small scoots and mopeds (under 50 cc) - both of which don't require tags in most, if not all, places. Those are usually restricted to 25-30 mph.

 

[why walk]

yeah, although I have passed my test, I am still restricted to 33 bhp for 2 years because I am 17. sucks

 

[drewpy]

its only a 5hp difference between 38 and 33.

If you want, why not email these guys, good reputation and ask them what's involved with restricting an xs400 as they have experience. (pretend your a new customer)

http://www.sportandcustoms.co.uk/Power restriction service.htm

I know of these guys and they have rebuilt a couple of xs400's

http://www.sportandcustoms.co.uk/Projects & builds.htm

 

[why walk]

Yeah, that's the thing, it should only be 5hp, but i was riding up a hill today at 47 and couldn't go any faster, which cant be right. My honda 125, which is knackered, could go faster than that.

 

[HoughMade]

No, that's not right. I would try advancing the timing a little. If there is any where in the engine such that the compression is less than stock (pretty normal), the engine can take a little advancing. Get the engine warm and at the proper idle speed, then advance and the idle speed should increase. When the idle speed starts to decrease, then back it off a few degrees. Oh, and I forgot to say, make sure it is static timed first- if your bike has electronic ignition, it will be. If not, follow the factory manual instructions for statis timing the point, and make sure the points clearance has been set, then advance as stated above from there. You may be surprised.

 

[why walk]

I will give it a go, Thanks

 

[HoughMade]

Oh...but when you ride after advancing, make sure you listen for pre-ignition "pinging". If you hear that, take it easy on the bike 'til you get home, then back the timing off a bit.

....this is all assuming that the carbs are clean and the ignition system is working correctly.

 

[why walk]

everything else was good, apart from the restrictors

 

[xschris]

Take them off

 

[why walk]

I could, but I ride a noisy bike through a city centre every morning. I cant afford to get stopped by the police because I will loose my license, which sucks even more than having a slow bike

 

[drewpy]

did you email the bike shop above and ask them how they restrict their bikes?

I would go back to the original shop and say there's a problem and get them to fix it. have you changed the bike's specs from original as you say that the bike is noisy?


not letting the needle rise to the top will cause problems in the top end and fuelling issues as the butterfly valve will be fully open letting in all the air, but the needle is restricting the fuel. I reckon that is a bad situation as a weak mix could cause engine damage!

 

[why walk]

Yeah, The PO put Dunstall exhausts on it. The mechanic says that's why it pulled at 42hp.
And I see, that's not good? so far I have only been riding it so that the butterfly valve does not open further than he needles rise up. I hope.
What damage does a weak mixture do?

And yes I did Email them, just waiting on a reply.

 

[drewpy]

pre ignition, melt the piston eventually.
why couldn't they restrict the exhaust with a washer? then you can take it out after 2 years

 

[why walk]

I don't know, i might have to look at getting it re-done properly, because this doesn't seem the best solution