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I'm starting with the 146 kit from SGR, high compression piston for big valve head, Z40 cam and springs from Dratv, and a ported lifan big valve head. I'm also thinking about using some modified titanium crf250 valves I have machined down to fit. Are there any problem I might have running this setup? Here are some pics of my head and the ti valve.
 

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Two things.

1. Get yourself some better springs, as I hear that the Dratv springs do not last very long at all.

2. If you are going to use the ti valves, spend a bit of money and have them coated with DLC or TiNitrate. This will help them last much longer. I have heard of ti valve stems rubbing thin at the center.



Other than that this set up should be good for 15-16hp.
 

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dratv springs will last 5 min and by that time you will have stuck a valve and probably destroyed the head. you can not use the trailbikes springs with the z 40 cam, the intake inner valve spring will bind.
 

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HACKMUNCH said:
dratv springs will last 5 min and by that time you will have stuck a valve and probably destroyed the head. you can not use the trailbikes springs with the z 40 cam, the intake inner valve spring will bind.


Springs from the TB race head kit have been working great for over 12 hours now. I am using the TB race cam which has .275 lift vs. the z40's .271 lift.
 

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did you test the head by hand before you put it on? i have built a ton of lifan heads and every intake inner valve spring binded so check your cam in about a week and i bet the intake lobe is a tad shorter now lol. this is why it pays to have an expert build races engines.
 

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HACKMUNCH said:
did you test the head by hand before you put it on? i have built a ton of lifan heads and every intake inner valve spring binded so check your cam in about a week and i bet the intake lobe is a tad shorter now lol. this is why it pays to have an expert build races engines.


Head was checked and built by an expert, I check the valves every week and the cam still looks great.

But since you are on here, why don't you tell everyone what springs you recommend.
 

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HACKMUNCH said:
did you test the head by hand before you put it on? i have built a ton of lifan heads and every intake inner valve spring binded so check your cam in about a week and i bet the intake lobe is a tad shorter now lol. this is why it pays to have an expert build races engines.


So, you are an expert then? Since youve built a ton of lifan heads and you know of this problem?
 

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Hack, these are the springs that come with the Race Head kit, the springs that are for the Race Cam, for the Race Head. So these springs are for that cam, maybe you have had a bad time with the stock springs and the RAce Cam.
 

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ok here are the problems i have encountered in the last 6 months building these lifan heads. I am doing this to inform everybody not to try and prove everyone wrong or anything like that. a little sharing of knowledge goes along way. 1st off TB valve springs are decent springs (at least the outers are) i do not recomend there intake inners due to coil bind issues. the problem with the tb honda race head spring set is that they are designed for a different stem heigth then what we have with the lifan head, now if your cutting your own seats this is not an issue because you can sink the valves as far as you like and get the stem height you need. second of all these lifan head tolerances are off from head to head (i am talking stem heigth)but not alot just like .2mm or so but that is alot when you run shi$ as tight as you can get and the tb spring tolerances on the inners are off a ton, i have had some inners collapse at 15mm and some as low as 14.2mm, with the z40 or the tb cam you need 14mm now with my takegawa r 20 you need even more but that is a different ball game. hope this helps everyone understand some issues. now for what i am running it matters what engine your talking about, my "monstard" runs crf450 kibblewhite intake valve springs with custom inner springs but i am running the high lift takegawa r20 cam with larger valves. now my new x4 runs kitaco hd valve springs shimed to the correct heigth with custom inners but i am only running a mild crower #18 cam for now (i have had the cam here for awhile and i want to try it for shi$S and giggles) hope this clears everything up and please try and stay clear from the dratv springs as i have seen and broke myself tons of these springs.
 

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here is a pic of a cam that has been run for 5 months, it had a little coil bind on the intake side and once it wore through the hardened surface of the cam it just wore more and more due to the stiff springs. i miced it and it wore off .26mm on the intake lobe.
 

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what valves are you going to use?? you might want to check and make sure the ends are hardened...sometimes using valves from a shim under bucket valve can cause mushrooming on the end of the valve because it was not hardened. I have seen this in person and on this forum...just fyi...
 
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