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Posted: 07/22/08 05:17 PM
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Posted: 07/23/08 08:42 AM
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wolf1
Guru
| Posts: 1064
| Joined: 11/07
Posted: 07/23/08 06:30 PM
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Posted: 07/23/08 08:39 PM
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hello. i had a 2003 kfx 400. it is the same atv. only difference is the plastic. the engine was designed for a dirt bike, but they tuned it down and put it in the ltz 400, the kfx 400, and the dvx 400. it is a suzuki engine though. it is a very good set-up. stock, they are faster than a 400 ex, but do have a little less torque on the bottom end. it handels well in the woods . very good suspension. ok the engine. it is a little harder to work on than a 350 warrior, or a 300ex, or the 400ex,just to name a few. it is a dual over head cam system. it has a long timing chain in it that goes over both cams. due to the chain design, it will stretch faster than a single over head cam engine. also the valve adjustment is much harder to do than a single over head cam system. it has what is called a bucket style lifters. to adjust the valves you have to pull the cams, and install shims under the lifters. reinstall the lifters and cams and then recheck your valve clearance. if you decide to do some of your own repairs, by all means get a GOOD service manual. NOT A HAYNES. they have plenty of them on e-bay. i buy the downloadable manuals to install on my laptop. also you need to keep an eye on the timing chain tension to see how much the chain has stretched. it is a ratchet type tensioner. i am not sure how many clicks, or teeth it has, but if it has 3 teeth left get ready to put a chain in it very soon. this is a simple check. takes less than 15 minuites to do it. if you are careful it will not tear the tensioner gasket, but you might want to have a new gasket on hand though. also people love to add rev boxes to the atv. this is ok, BUT if you do this you will need to upgrade the valves, and valve springs. the valves are a 2-piece valve. you need to get stainless steel valves, and there is a kit out there called a DRZE KIT. it has the dual springs with it, also a thinner base gasket to bump the compression up to 12:2:1 from 11:3:1 which is stock. a good form to check out is z400central. the reason you need the heaver springs, and better valves, is the after market rev box lets the engine rev depending on the brand you get, 1,000 to 3,000 over stock. the engine can handle the 1,000 easily, but the valve train is not stable at these excessive rpm's. it will float, or drop a valve, and then it will come to a very harsh stop. big money to repair this. this is a nickeasil coated cylinder. not cheap.(the spelling is probably wrong, sorry). they do require a little more maintance, but are very good all around machines though. if you are going to add a exhaust, in my opinion, yoshemier is the best one. but remember to rejet the carb, and remove the filter lid, or install a lid filter to let as mush air as possible to it. hope this helps you out. ps. you can find the place that sells the drze kit on z400central.com. you might have to search for it. i think the guy has a store in the forms. hope you good luck. it could blow up the next time you ride it. any of them could though. my 86 trx250r might scatter the next time i start it, but i know it runs fine right now. oh yea. people might tell you that they are running a rev box, and still running the stock chain, valver, or valve springs. they might be, but some people might want to take that chance. i wont gamble if i know something is not right. just my 2-cents.this is the name of the sight for the drze kit. i did the leg work.( www.AdvantageCycleLC.com ) good luck.
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