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Author Topic: Project "walrus" Yam XS 750  (Read 26172 times)

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #30 on: Aug 10, 2016, 04:20:05 »
Thanks man!any ideas on my last post (spark problems)?

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Offline datadavid

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Re: Project "walrus" Yam XS 750
« Reply #31 on: Aug 10, 2016, 04:45:31 »
If you can find someone to weld them for not much, then they would be great. If they want to charge shop rates then might be better getting the Triumph carbies.
Just check that the pitch and mounting boss on the engine side matches the mounting rubber boot internal diameter on the triumph carbies.
I am using a triumph 1050 header on the 896 and the pitch was perfect, but the head interface needs work to make it fit. The triumph carbies Dave used were a simple fitment. Was that correct Dave?
It should run OK on the Mk 1 carbies, at least to see if the rest is OK.
Cheers
Tim
It was very straightforward, bolts straight on to the stock rubbers.

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #32 on: Aug 10, 2016, 04:53:49 »
Any ideas on my spark problem data?

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #33 on: Aug 10, 2016, 05:09:29 »
Hi Ryan
If you have good spark on one cylinder then it is unlikely to be the CDI unit. Each cylinder has its own coil and high tension lead. My 750 was week on #1 and it was the high tension lead. If you have some spare leads and coils on the other bike, then start by swapping the lead. If still no good try swapping the coil the coil.
See where that get you.
Regards
Tim

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #34 on: Aug 10, 2016, 05:23:50 »
Hey tim thank you!
By lead you mean the thick cables coming from the coil going to the spark plug boot dont you?

What do you say concerning the main chain slack i described?

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #35 on: Aug 10, 2016, 05:26:32 »
Ryan
For testing make sure the battery is fully charged. My harness was cactus and the bike was not charging. When the battery lost charge the engine started to miss on one cylinder and as the charge dropped it would not run at all. It could be the regulator if the battery is low. If your battery is fully charged then keep going with the high tension leads and coils.
To test the regulator you should be getting a voltage better than 14volts across the black and red wire coming out of the regulator.
Good luck
Tim

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #36 on: Aug 10, 2016, 05:40:41 »
Ryan
Yes cables coming out of the coil and going to spark plugs - the caps can also be faulty and leak the spark!!!
The chain you can see through the oil cap is the primary chain which transfers power from the crank to the clutch - they are a known weak point. Many people on line make up chain tensioners to "fix" the problem. The good point is that on the XS750 they are bloody easy to take the side covers off and fit a new chain as it is on the side of the engine. You can change the chain without removing the engine from the frame ;D. All the 4 cylinder engines have the primary chain going through the middle cylinders. and are a lot more work >:(.
Sounds like it has a bit of slack, but they are never "tight". The top is the tension side when driven and the slack is down at the bottom where there is a little extra room. If you are not finding aluminium filings in the engine oil then it is not hitting anything and it is not you top priority. It can wait until you are ready to change it - they are relatively expensive.
Good luck.
Tim

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #37 on: Aug 10, 2016, 06:06:31 »
Thanks tim!i guess then i will get new plug caps in combo with the new leads.
How are the leads mounted in the coils?

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #38 on: Aug 10, 2016, 06:22:34 »
Ryan
You need to take the screw cap off the old cable and put it on the new cable. Then there should be a metal screw thread poking out of the coil that you screw into the wire on the new lead. Then you screw the cap down on the coil to clamp it all tight.
I take it that your battery was fully charged?
Cheers
Tim

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #39 on: Aug 10, 2016, 06:34:47 »
Ok tim!
The battery read 12.3Volts without the starter running,i guess it needs a good charge since I already tried to start it a few times (battery is new).

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #40 on: Aug 10, 2016, 07:03:39 »
12.3 is marginal if the regulator is stuffed. Should be closer to 13V if it was a freshly charged battery. Suggest you charge it and see if  you get good spark. In the past I have hooked up a car or boat battery with jumper leads just to test things http://www.dotheton.com/forum/Smileys/default/wink.gif
Tim

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #41 on: Aug 10, 2016, 07:27:09 »
Ok tim!so you connect a car battery (running motor) directly to the minus and plus terminals of the xs battery am I right...then i will do it this way next time!

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #42 on: Aug 10, 2016, 07:42:12 »
correct

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #43 on: Aug 10, 2016, 07:46:20 »
Superb! :D then I will try it this way!

The PO told me that he thinks the rectifier is fried cuz the lights and control lights won´t come on (in all key position), he gave me a new unit, i guess I will try to connect the new unit to when I try the things you stated.

There is a malconnection too at the cables coming out of the rectifier (black cable came loose), could this also cause this ignition problem, i tried to fix it,maybe there´s still no connection?

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #44 on: Aug 10, 2016, 08:07:42 »
Yes the cables and connectors are 40years old, there is probably more than one faulty connector. On my bike it would not charge, the rectifier was OK, the problem was just shitty connections that were worn out and corroded. The black cable out of the rectifier goes to earth. I hate electronics - it is more like black magic to me!!!!! In the end I just had to pay a guy to fix it http://www.dotheton.com/forum/Smileys/default/angry.gif.
Cheers
Tim