XJ750 Midnight Maxim problems

Hi all,

Just to introduce myself, I'm Mike, I am a new biker and passed my test 2 weeks ago.

I have recently purchased a XJ750 Midnight Maxim for a tidy £200. When I bought it, it was a non runner. I'm not a mechanic, but i can do basic stuff so I cleaned out the carbs (which were not that dirty), added a fuel filter and replaced one of the ignition coils (as 1 & 4 were not sparking) and managed to get it running for around a week however this morning it would not start. I have checked and there is a decent spark on all 4 plugs.

I did some seaching on this issue and it was suggested to "Set the petcock to prime", I have never heard of this term before but I found this is a setting on the fuel switch. I had already left this on prime when I initially fixed it a weeek ago, would this be the cause of my issues?

If not, can anyone suggest the next step? I have read of people putting starter fluid or petrol directly in the piston, should I try this?

Thanks in advance

Mike

 

Make sure your battery is charged up properly, as you may think its fine as it spins the motor quick enough to start it, but the thing is, that may be so, but it may not have enough charge to actually fire the bike up.

Where are you mate? It sounds like you are in the good old UK

What you need to do on here is fill out your profile page more, with your location and also in the signature section, put what bike you have and its year. I know you've already said it's a Midnight Maxim 750, but put the info in the sig

 

Oh and I should have mentioned in my last post, before you go riding on it, check out BigFitz's Delamination Post: www.xjbikes.com/Forums...15874.html and check those rear brakes. your life depends on it

 

Thanks for your reply Smurf667, Yes im in Sheffield Ive updated my sig and profile as suggested. Ive put the battery on charge now and I'll let you know how it goes.

 

Please do, and thanks for updating your info too. The reason for asking people to do that is, you could have someone close by, that may be able to help you with any problems by coming to pop round to you.

You are sort of in luck in one respect, as I'm not that far from you, I'm on the border of Nottinghamshire/ Yorkshire/Lincs, right next to the A1

OK, you say you've recently bought it, do you know anything about it and it's history? was it bought from a friend maybe?

The reason I ask you that will hopefully become clear to you as you read on.

You say that you've cleaned the carbs, what did you do? Do a search on the site for "Church of clean" and "clunk test", you may be surprised reading them, if you've cleaned the carbs to that standard, brill, if not, take the carbs off again (sorry about that), and make sure you do do it to that standard and make sure they pass the clunk test. Bench sync the carbs, and wet set them.

After that, Check the valve clearances to make sure they are in spec, if not, then you need to get them in spec by changing the shims, again you'll find all the info you need on here.

You need the valves in spec to sync the carbs once back on the bike.

 

Thanks again for your reply.

I think I (or you) managed to figure out the issue, I went over a bump the other day which hit the exhaust, i didn't think to much about it at the time. On a closer inspection whilst the battery is on charge (The bike is currently in the kitchen) its made a hole at the underside of the exhaust. I hooked the battery back up, covered up the hole with my hand and it fired first time. I'm not sure if this was a flat battery or lack of back pressure from the exhaust (This is a guess and I might be very wrong!).

Thanks for the link on the back brake, ill check that out. Is a shaft drive wheel much harder to remove than a chain / sprocket type? I have a Haynes manual for guidance.

I don't know too much about the history, I bought if from a work colleague who had it for around 4 months. He paid £600 for it however he broke down on the way to work on it one day and the local bike shop quoted him £350 for a carb clean and a ignition coil so he sold me this and bough himself a new one.

I followed this link for the carb clean instructions, http://knol.google.com/k/how-to-clean-a ... right-way# I followed it to the letter and boiled the various parts. Do you think I should strip it again or only mess around with it if I have problems?

Sorry for the novel, one final question please In regards to the valve clearances, shall I still do that even though its running or do I only check it out if I have future problems.

Thanks again for all you help.

 

Valve clearances should be checked every 5000 MILES, after the initial check at 3K miles.

Valves also need to be in spec before any carb sync adjustment.

Look in "XJ FAQ Suggestions" for a number of helpful tech articles and how-tos.

 

Thanks Fitz, you beat me to it