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2003 suzuki ltz400 big bore
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Discussion Starter · #1 ·
Hi all.

Been lurking forums for a while and have received a ton of help already. Bought a used ltz400 that I've been trying to get running. Just looking for helpful hints so I know I'm in the right direction.

Bought non running but just came back from shop having new head (big bore 434cc), new piston and rings, cam chain done. I just can't get it running now.. Here is what I've already done....

Did coolant flush and oil change
Good spark and new plug (checked stator as well and checks out fyi)
Replaced oil pump gear and checked oil pump
Cleaned carb and installed dynojet jet kit (155 main etc) I double checked this also but I'm not sure it's giving fuel for some reason as spark plug never seems real wet)
Checked valves and fixed (they were quite out.. Now within spec) and double checked again after rotating and back at tdc.
Timing is bang on.. I double checked it also
New battery

Next and only thing I can now think of is if new rebuild has busted rings and no compression (or very low) and/or carb for some reason I can't see or tell isnt working.

I'm only well versed in repairing small honda motors so this is all new to me and a bit more advanced.

Is my next step to verify compression and if it's good, replace carb?
 

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Check Compression to make sure nothing is off there, If that's good does it fire on ether? Try putting petcock on prime , check and make sure fuel is flowing . Check back in after these steps.
 

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2003 suzuki ltz400 big bore
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Discussion Starter · #3 ·
Check Compression to make sure nothing is off there, If that's good does it fire on ether? Try putting petcock on prime , check and make sure fuel is flowing . Check back in after these steps.
Would low compression cause it not to 'pull' fuel from carb? My old mikuni flat side carb used throttle to open slide but looks like these work on pressure to open slide?
 

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If the quad is low on compression it will not fire, I am not sure how much the compression affects fuel being sucked from the carb but I am sure it does some.
 

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2003 suzuki ltz400 big bore
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Discussion Starter · #5 ·
Next question.... My cams are timed properly according to marks and tdc, But...... Lobes aare not at 10 and 2.how is that possible? Lobes look more like 12 and 2
 

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You don't have the cams backwards do you? They should be at 10 and 2.

I suspect it's a timing issue
 

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Discussion Starter · #7 ·
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This is how cams are.. Tdc. Ex cam and in are correct. Timing is correct. I just rechecked as thought they may be set on non compression stroke.

So.. What the heck... Cams somehow twisted? Never heard of that
 

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If you are sure everything is correct, the Gear could have spun on the cam, Can and does happen.
 

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2003 suzuki ltz400 big bore
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Discussion Starter · #9 ·
Well.. You can see by pictures I have them lined up (2 and 3 at top) with correct spacing (15 pins on chain) at tdc and they are not sitting right. That'd explain why it won't run anyway.

So.... Sounds like need new cams then?

I'd also not be able to confirm compression or anything either until proper correct?
 

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Order a set of stage 2 Hot Cams, Priced well and will give you a little bit of power nothing crazy though. I would hold off on compression test until things are correct with the cams.
 

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Discussion Starter · #11 ·
Order a set of stage 2 Hot Cams, Priced well and will give you a little bit of power nothing crazy though. I would hold off on compression test until things are correct with the cams.
Next point of concern.... If timing chain broke, spun the pressed on sprockets, my valves could be toast if piston hit them being out of time or?

Sounds like I need to take the head off now too and check. This machine is becoming a nightmare
 

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It is possible but I don't think your chain broke unless ti did and previous owner tried to fix it an dgave up.
 

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Discussion Starter · #13 ·
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Exhaust valves sure don't look like they are seating.

Intake valves don't look terrible (can't see any light at least)

Is it worth buying tools and parts to get them done or just take em to the dealership??
 

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It seems like you have some knowledge, I just rebuilt mine, I used Wiesco Valves and replaced the seals and guides, I would get a new Chain as well.
 

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Discussion Starter · #16 ·
Took valves out and yup... They are bent.

So.. I'll order some new ones. If I get stage 2 Ames, I need drz springs? And I keep reading not to lap valves so how do I clean up seats with new valves?

Also, how can I tell if my guides are good or not? I've searched a fair bit on replacing valves but I can't seem to get good info on seat prep or how to check/change guides
 

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Honestly i am not sure how to explain it, but its not a bad job, The DRZ springs should be used if getting a higher reving CDI Box, but I would recommend doing them while you have it a part either way, I think everyone is going to have their oppion on what brand to run, I honestly think you will be fine with Wiesco, Ferrea or KW. Is the piston ok? You could check ring end gap while you are in there and replace if needed, I would use DRZE gasket while its apart and probably replace teh Chain guides as well. I just did my sons and replaced everything.
 
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Discussion Starter · #18 ·
Ok so ordered hot cams stage 2 and full set of kibblewhite valves and springs etc. And yes...my wife wants to kill me.

My question (and hard to find an answer it seems) is how do I know if my valve seats are good? They 'look' okay (I just wiped them clean etc)

Since I can't use compound on the new titanium valves and my old ones are bent, what's the best method to get a good seal and how to I check seats?
 

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I am going to have to let someone else see if they can guide/explain it to you. I am going to assume you will probably be fine , I did replace mine but I don't believe it was really needed. Make sure you do the timing chain and guides as well.
 

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The only way to know for sure if your seats are good is the have them cut, or do a light lap, which is dubious with those valves. Or you could ignore it, and try gas in the chamber, see if leaks past the valves. You could buy 2 new wiseco valves and use those to lap the seats as well.
 
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