CBR400 Problems

14 posts / 0 new
Last post
CBR400 Problems

Can any of you guys help with this? My gullarm has been having problems recently.

The bike broke down two and a half weeks ago, it just stopped. It has done this before and the mechanic fitted a new regulator rectifier. That was fine for about 4-6 weeks and it did it again.....it needed another rectifier. That was fine until recently when it broke down again and again the rectifier had blown up/over heated.

The guys at Zoom tried to find out what was wrong but they couldn't find anything. There was something causing the electrics to put out too much energy that was causing the recifier to over load.

I've since had it delivered back to the shop where I bought it from.

Can anyone help me out with this?


just a guess... did you replace the battery as well?if the battery is fecked then it will play merry hell with the rest of the electronics.

yep could be the battery damanding too much juice and being an obligeing sort of thing the rect. will try its very best to suply it even unto death!. Or u got a huge leek of leccy somwhere and this has the same efect... I presume u dont run ur batter realy falt every day then expect the thing to recharge on the move?...or u havent got a huge battery fitted?

Make sure it's the right battery for the bike, then get an Optimate battery charger, and use it.

Not much of a mechanic as this post is about to demonstrate but I had a not dissimilar problem with a car I once had. The problem turned out to be the wrong model of distributor fitted. So check that all the electrical components (alternator, HT coil etc) are the right ones for your bike.

Thank you very much for your feedback guys! I'll be passing on your comments to the mechanic. btw I did actually change the battery earlier this year. I bought it from the shop where I bought the bike, so I'm assuming that it is the right battery, I hope. I'll have a word.Cheers.

Check the wiring going right back to the Rotor and stator. There will be 3 to 6 wires, the are prone to getting v hot, if two or more have heated up, they will have melted the wires and this it what will be frying the reg/rec. It might not even be the reg/rec. If the one of the fused wirs is a return feed, it wont allow the battery to charge.I had exactly the same problem with my XTZ750, I found the problem when the it killed the first reg/rec.There will be wires coming out of the left hand engine casing, they will run into the wiring loom right back to the reg/rec and then to the battery.If they are melted, dont let the shop replace the wiring loom, get the bike home, take the offending wires out of the loom, unplug then at both ends, find someone that is good with a soldering iron and get them to put in a new run of cable.I will take about 2 hours to get the wires out, and a pint for the solderer! To check if it is the wires without taking them out, check to continuity of the wires with a multi meter, the manual will tell you what the readings should be.Your mechanic sounds like a YTS boy. He should have been looking for why its done it in the first place, rather than replacing things at a stupid cost to you. Hope this helps

I spoke to the mechanic today told him what you guys had said and he said he agreed there might be a problem with the battery so he replaced it with a new one. He also replaced the heat thingy (that's technical talk for the bit that takes the heat from the rectifier) and a new rectifier. He's still not 100% what's caused these problems. He said the wiring is fine, to and from the battery to the rectifier. Anyway, I'm going to collect it tomorrow lunchtime, so I'll find out if what he has done has corrected it. Thank you again for all your help guys.

Its the wiring from the rotor and stator that needs checking mate, it there is a problem it will be in the loom, the best way is to get a multi meter on it, have you got a manual??? What year CBR is it??? model etc???where abouts do you live??

It's a 1989 Gullarm. I've got a haynes manual, but I don't have a multi meter. Is that something that you can get easily at a bike shop?I live in Bicester, Oxfordshire.

any decent electrical shop will have a multi meter, your mechanic should have amulti meter.You'd need to find the resistance figures in your haynes for the wiring between the generator and the reg/rec.Unplug both ends, put the meter od one end of each of the plugs, they should all read what the manual says.The manual will alos tell you which setting to put the multi meter on. Its a very easy test to do.If any of the wires read v little or dont read at all, then its a case of new wires.If ya wanna hand, I'm only in london

Just so ya know, the 400 has a permanant magnet regulator, so there are only stator windings. You should check that all these are ok and check the open circuit voltages that these are producing. I had a 400 and it ate a generator and 3 or more reg/rects and 3 batteries. I found that a reg should last a year or so, but I had one pattern unit last weeks. The 400s have dodgy charging systems and produce too much voltage and blow units. It may simply be that you need a new reg/rec and that the last one wasn't up to the job. Send it back to the shop and get them to replace it if it lasted that long. The one I had that lasted weeks I sent back to the supplier and got a replacement.One shop lookeed at the system and said the bike produced too much voltage, but I think they all do that!

Let us know the result on this one mate

I've had her back a week now and she seems to be running fine. In fact it's just so good to be able to go out on her again. I asked a friend who came to visit if he could help me out if I got a multi-meter but he said it's a bit too technical for him and he wouldn't know where to start. So what I'm going to do is take it up to another mate up in Northampton and see if he can help me out.

Log in or register to post comments