predator 670 vs vc460

[slonomo]

Originally Posted by sho305

I've hit 38gps on a road. Last time I only hit 36 but have been changing setup in my clutch and not sure about tire pressure. Soft tires slow you down. I ran mine for a summer with stock springs and rockers, it would not go over 4500 or so. I did not rev past 4K for a tank of gas I think. 4K should be safe if you don't keep it there, you can run 3600 all day with a new stock engine 4K is not far away but don't keep it there at first. I ran plain oil at first.

Zinc is good for high pressure spots, like cam shafts. It is good in small splash engines because the rod is high pressure as you have no oil pump to keep oil in there. Most break in oil have zinc, special lube for new cams is full of it.

Should have clarified....thanks Sho! Zinc is good for flat tappet engines. That's the "high pressure" deal. Lots of wear on the cam due to the lack of hydraulic lifters. Zinc helps with that. Just good insurance with these engines.

[curdog71]

Originally Posted by slonomo

It is possible to get a batch of bad springs. Those springs come from China, so you never know what you are getting, prob cost 5 cents to mfg. The Comp Cams springs will no doubt be better metal and quality, although they are still probably made in China, lol, don't know for sure.

I broke my engine in with conventional oil, ran it on the bench at idle until it was warm. Then I ran it at approx 2000 rpm for 5 min, I adjusted the throttle to hold it there. Repeat 3x. Changed oil. Added zinc.

After installed, I drove the cart around normally, but no full throttle runs, no towing, no loads. Putted around for a few weeks, prob 20 hours or so. Changed the oil. Added zinc.

At that point I drove normal, and made a few high speed runs, not to exceed 5000 rpm for more than 5 seconds. Drove this way for a few months.

Never broke a spring. Never broke a rocker arm. Never bent a pushrod. Lash loosened up on me, so I rechecked that several times in the first few months. After that it was good to go.

My engine will rev past 7000 rpm with the big carb on it. It topped out at 42.6 mph at 7000 rpm, if my memory is correct. I have never revved past 7100, she's screaming at that point. Once I reached that rpm I shut it down and drove slower at 4000 or so. It runs super nice between 3000-5000 rpm, lots of pull, sounds really good.

I was using the 94c style clutch with mine, which probably held me back a little. I've heard the 780 really works well on these engines, and would probably help me gain some acceleration. But the midrange and upper rpm is where this engine shines. Just not made to do high rpm runs for long periods of time.

what carb are you running? I still have the stock carb that came on the 460

[sho305]

The Kart guys swear by it, though they are beating their clones hard. They like to use Royal Purple and Lucas kart oil. Some is $12/qt but guess a gx200 does not take much anyway.

[curdog71]

Originally Posted by curdog71

I totally agree with you jeff70, Vegas Carts have just completely blew me off after I started having major problems, I know they are a site sponser and so forth, I ordered my engine and complete installation kit from them at a cost of 1400.00 dollars, never complained about the price I just saved up and paid it when I got the money, made my order on jan 26 and got my installation kit and engine in a timely manner, but not the 780 drive clutch it was on back order for two weeks...I get everything installed and i'm waiting for the clutch while my warranty is ticking away, had a few MINOR issues with the engine and VC was quick and speedy about sending me what I needed...keep reading... one small issue was the soft cheap aluminum starter/gen pulley that I received with the installation kit, it did not last long and cracked, they were very helpful at getting me a new one, and when I received the new one it I realized they had upgraded to a better quality one... next minor issue was my fault because I jetted the main jet too big and wasn't sure were or what to buy so I called and asked to buy one and they volunteered to send me one no questions asked, OK...this is were the trouble begins, I finally get this thing running right were i can break it in nice and easy, after about 20 or so hours of babying this engine around I can see what it has got.. well after a few runs over 5000 rpm and many checks of valve lash it breaks a valve spring in half, and drops exhaust valve on the piston, valve is bent and the piston survives with only a scratch, so I call VC and they kindly send out a new replacement head, at this point I was really happy with their service department, just not happy with the engine being down and my warranty ticking away again...well after a week or so I get this thing back together and get a few days out of it and the same thing happens again, valve spring breaks drops valve and dents piston this time...VC is concerned at why this is happening and tells me this is very very rare thing to happen, I send entire engine back for a replacement one, more down time, lots of work and warranty is still ticking away.... I call and check to see when they can get the new one out and they tell me they are waiting on new style valve springs from comp cam, I'm thinking good deal better springs may hold up longer, well 3 weeks later my engine comes in, which was today....I was told I have no warranty on this new engine because it is a complete replacement engine, even though my original warranty still has a few days left, I don't have the 1.3.1 rockers on my new engine, I have the stock rockers now and I had 1.3.1 on my original engine....I have sent several emails to VC since friday to find out what they think the problem was with the springs breaking since I was told I was the only one having this problem, just being cautious with this new engine since it doesn't have ANY warranty and making sure it wasn't something that I did and don't want it to happen again, because i'm really tired of the breakdowns and all the work that I have put into this...... no response from them at all...I did call today and talk to a sales person not a tech and he told me they cant get the 1.3.1 rockers anymore, I ask him why I was the only one having this problem and he said I just got some bad springs, hmmmmm....twice in a row bad springs and as many engines they sale Im the only one having this problem? I just feel that Ive been blew off because of the problems ive had with the engine, I did get it installed today, started and idled it for a few minutes, just wondering if anybody else has had problems with their valve springs?
any advice will be appreciated thank you.....

update on the new engine... running good so far havent ran it really hard yet, no problems yet.... I suppose I will have to eat crow because Geoff at VC must have just been busy because he has gotten back to me many times now and has been a big help at answering my questions with the replacement engine....