92 Z71 Posted December 19, 2008 Report Share Posted December 19, 2008 I'm still gathering parts for my rebuild and just had a question with 4mils. I've got to swap cases and was thinking since it was coming apart it would be a good time to build a 4mil. But would it be a bad idea since I will be using a -1 swingarm? I don't want to be wheelieing all the time. How big of a difference is it between stock and 4mil? Quote Link to comment Share on other sites More sharing options...
fastrthnu Posted December 19, 2008 Report Share Posted December 19, 2008 I'm still gathering parts for my rebuild and just had a question with 4mils. I've got to swap cases and was thinking since it was coming apart it would be a good time to build a 4mil. But would it be a bad idea since I will be using a -1 swingarm? I don't want to be wheelieing all the time. How big of a difference is it between stock and 4mil? I have (had) a ported 4mm motor making just under 80hp on a -2. Yeehaww!!!! :cool: Just dont plan on drag racing on any hard surface or you grab bar is going to be PISSED. Quote Link to comment Share on other sites More sharing options...
278 Posted December 19, 2008 Report Share Posted December 19, 2008 There is a pretty big difference, because your gaining power from the 4mil crank, plus you have to get your cylinders ported for it and use forged pistons and you upgrade the carbs, etc. so if it was just the crank there wouldn't be a a huge difference, but everything else that you have to do along with it there will be a night and day difference. I would say just run the -1 and see how bad it is if it is then find a stocker Quote Link to comment Share on other sites More sharing options...
deckheight Posted December 19, 2008 Report Share Posted December 19, 2008 Ahhh! The wheelie part is fun... It's the unexpected rear wheel hookups and subsequent high speed loop-de-loops that suck! Quote Link to comment Share on other sites More sharing options...
BUILDER Posted December 19, 2008 Report Share Posted December 19, 2008 Ahhh! The wheelie part is fun... It's the unexpected rear wheel hookups and subsequent high speed loop-de-loops that suck! There is much more to think about when you are doing this. If you are going to go with a 4mill your cost will be a lot more than just going back stock. I ride a 4mill here in Oregon also lol i would not want to try and ride mine with a -1 swing arm. I have a +5 swing arm on mine and i have no trouble getting the frontend up in the air. If you are wanting to trail ride in the woods and ride sand dunes also i think a nice port job would serve you better than a 4mill would. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted December 20, 2008 Report Share Posted December 20, 2008 If the motor is set up right with a cut set of domes and no plate, with the right porting/pipe combination you will be just fine with a -1 swingarm. The porting/pipe combination needs to be set up for low end grunt with a smooth power band. I've built trail orientated 4mils for guys with stock and - lenght swingers and I've also built dune/drag 4mils that need +8 swingers. It's all in the setup. Quote Link to comment Share on other sites More sharing options...
BUILDER Posted December 20, 2008 Report Share Posted December 20, 2008 If the motor is set up right with a cut set of domes and no plate, with the right porting/pipe combination you will be just fine with a -1 swingarm. The porting/pipe combination needs to be set up for low end grunt with a smooth power band. I've built trail orientated 4mils for guys with stock and - lenght swingers and I've also built dune/drag 4mils that need +8 swingers. It's all in the setup. slobanshee i have a question for you. If the bike is set up to were it is easy to ride with a stock or less than stock swinger it seams like to me you are giving up power? Dont get me wrong i am not arguing with you it is just a question. I understand having the power in a different spot but it dont seam like to me you would be getting the full potential out of your 4 mill. Would a good port job not do the same thing? Just trying to understand better what you are saying. :shrug: Quote Link to comment Share on other sites More sharing options...
92 Z71 Posted December 20, 2008 Author Report Share Posted December 20, 2008 Thank you guys for the responses. I think I'll just keep it stock crank for now. Maybe if i change the bike up in the future with a plus swinger I'll go to 4mm. Quote Link to comment Share on other sites More sharing options...
278 Posted December 20, 2008 Report Share Posted December 20, 2008 slobanshee i have a question for you. If the bike is set up to were it is easy to ride with a stock or less than stock swinger it seams like to me you are giving up power? Dont get me wrong i am not arguing with you it is just a question. I understand having the power in a different spot but it dont seam like to me you would be getting the full potential out of your 4 mill. Would a good port job not do the same thing? Just trying to understand better what you are saying. :shrug: What he is saying is if you build it for drag or dune you want a peaky like power band, think of a tall steep mountain, but on trails you want a more controlable longer power band like a long rolling mountain, yeah you won't have quite as much power but your not talking the difference between lets say 70 and 90 it would be more like 78 and 85 (hypethetical numbers). In tight trails and mx tracks you really don't need all the power in the world so you build a smooth long power band. That is why I didn't see a need for a 4mil in my motor, because all I do is ride tight trails with some open trails and occasional small hill climb for fun. In this case if you were to have Brandon do your work (Slobanshee06, which is a great choice and after my build the only one I will send my motor work to anymore) he would go with an agressive trail port and push the limit of where long and smooth meets peaky. Hope that helps Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted December 20, 2008 Report Share Posted December 20, 2008 The 4mils best advantage over a stock stroke is the torque capabilities of the motor to be set up for a broad power band. Along with the stroke comes some extra displacement which in turn adds to the hp capabilities of the motor. Any time you set up a banshee engine for trail/woods/mx use you are going to be giving up top end power potential in favor of useable bottom end torque. It is almost always a tradeoff, most mods that add low end are going to rob you of some top end. The important part is making the power curve of the engine the most useable for the environment it will be use in. As far as a good port job doing the same thing, you are never going to achieve the same kind of low end torqe as a properly ported 4mil with a ported stock stroke. Quote Link to comment Share on other sites More sharing options...
deckheight Posted December 21, 2008 Report Share Posted December 21, 2008 Ahh man! Don't let all this spook you. Bottom line is that if your comfortable on your current set-up (stock stroke) with whatever type riding your doing and nothing else changes other than a +4mm crank, you will probably love it! 4mm added stroke in and of itself is not all that! It's all the other stuff that usually goes along with it (higher compression ratios, porting, carbs, pipes, etc)... It aint cheap! And don't forget rider ability (see comfort level above) that has a whole lot to do with it also... Thus my earler loop-de-loop post, because I don't have any... Found that out a couple months ago Good luck Thank you guys for the responses. I think I'll just keep it stock crank for now. Maybe if i change the bike up in the future with a plus swinger I'll go to 4mm. Quote Link to comment Share on other sites More sharing options...
deckheight Posted December 21, 2008 Report Share Posted December 21, 2008 motor builder, where do you usually ride at? Ever make it down south coast? Quote Link to comment Share on other sites More sharing options...
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