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new valvs /weak starter (ltz 400)

4K views 32 replies 4 participants last post by  piki 
#1 ·
so...
finished the new head , with new valves , new chain with new guide as well, got oil n coolant n fuel ,
came to start it up after all this work and waiting, and checked compresion,it is 39 psi, tho engine not worm (daa) , and for some reason starter motor seems pretty weak(with plug in , and with plug out) , like its not sound like strong starter.
valve clearence is good , and tested with big battery at 12.8 v
got spurk, and check the timing 100 times its 100% correct,

bad starter? or something due the compression?
should i try kick start it?
 
#2 ·
btw its kw valves , and i didnt lap thm, and didnt cut seats (looked decent)
 
#3 ·
Possibly. The contacts get corroded inside if it has been used in muddy or wet conditions. Try to pull-start it and see if it fires up.
 
#4 ·
Its not going to start anyway if the compression really is 39 psi..
 
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#5 ·
i will try pull start tomorrow, about the comp check ... the engine cranck realy! slow , so reading might be inaccurate, i will try , and then i will do leakdown test, and will replace starter with another ltz that i have and will see from there....
 
#6 ·
bad ground ?
 
#7 ·
i do have continuity , but how do i know if ground is bad?
 
#8 ·
remove ,clean and replace all points where wires are attached at battery and starter
 
#9 ·
update, piston was in bad condision, so i order new piston with cylinder 434 cc, ( any thought on that?), and i did the valve seat as well,i will deal with the starter issue after i done with engine i guess.
434 bore kit from amazon will fit good?
 
#10 ·
#12 ·
thinking all 4 are head bolt washers
 
#13 ·
the bore kit is good?
i dont think i have any washers currently on my head bolts
 
#14 ·
I’ve never heard of that brand. Yes, there should be washers on the head. No idea what piston brand or compression ratio it is. Welcome to amazon!
 
#15 ·
#16 ·
i also can reuse my cylinder,and just buy apiston from a local dealer at 150$,and i did took the cylinder to the shop , but i rather buy a piston with cylinder in 1 package, and the guy told me that this cylinder is not 100% anymore
 
#17 ·
lots of questions,
but i just noticed that most likely ,y old valves were titanium(theu are black), and i only bought KB ss valves with no springs, does the oem(hope so) springs must be replcae?(they are single springs)
how can i can confirm that the old ones are titanium?
 
#19 ·
ok so here pic of old valves(not black lol)...

realy appreciate all the help :)
 

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#20 ·
Another update...):
opened the starter, was small short there and its burned, simple 1 from ebay/amazon will do? or there is good one?
 
#21 ·
Those are stock valves that you removed. As far as I know, you should run the dual springs with KW valves. Heavier valves require more spring pressure and the stock springs do wear out and get weak.

Any new piston you buy must be matched to the cylinder. If the piston is bad, the cylinder usually has some damage, so most people replace both as a kit. Since they are already matched together, all you have to do is gap the rings (file them down to within specs) and bolt it on.

The OEM starters are not cheap, probably $300. I have no experience with aftermarket starters, but I assume they’ll work for a little while, at least.
 
#22 ·
Jet u are the man...
ordered cylinder+weisco piston, also ordered the KW drz duel springs...

starter i ordered something at 40 $ with 2 years warrenty , so seems fine to me
thx for all the help, i will update when the engine running(hopfully)
 
#23 ·
btw whats the best way to file the rings?
 
#24 ·
There’s an actual “ring filing“ tool you can get from most auto shops. Looks like a tiny little table with a grinding wheel sticking out of it and a hand crank. Made so you can lay the ring flat on it and it files the edge square, leaving the “burr” of metal pointing away from the cylinder wall. Pretty neat and cheap.
 
#25 ·
I have had good luck with the chinese starters..
 
#26 ·
aight ty , i will update after everything is in place,

about th ring filler , hope i wont need it , wallet to tight atm...
 
#27 · (Edited)
OK
so finaly finished my build ,weisco piston with cylinder 90 mm bore, did a compression test (i know it was cold engine) came out as 80 psi,tried to start the quad , whould not fire up, so i did a leakdown test and had some very lightly air in the cranckcase, opened everything again and checked the rings again.
weisco said in instruction to divide the bore in 25.4 (=3.54 ) then do double it 0.004 in, adns 2th in 0.005
the first ring gap was 0.014 in, the 2th was around 0.020 gap, is that seems right?
also the cylinder and the head gasget that i had (new) were diffrent from the gaskets who came with cylinder and piston from weisco, was diffrent in thickness, what does thickness means to compression?
was my foult that i didnt used the gasket that weisco sended?
had fuel air and spurk , not sure why she didnt fire up beside copression faliure of some short....
 

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#28 ·
I would expect the rings to leak a little since they haven’t seated and no oil on them. I doubt that is your issue. Seems to me it needs to run first for an accurate comp test. May be some other issue.

Thicker head/base gaskets would slightly change compression ratio, but shouldn’t change the value on a compression test by much.
 
#29 ·
any idea why it whoulsnt fire up ?
some leads? im pretty sure i tsested eveything from spurk to fuel...
 
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