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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> DR650 cam on Savage- more compression Required? /cgi-bin/YaBB.pl?num=1649873691 Message started by wheelbender6 on 04/13/22 at 11:14:51 |
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Title: DR650 cam on Savage- more compression Required? Post by wheelbender6 on 04/13/22 at 11:14:51 I have read good things about the stock DR650 cam on this site. However, I noticed the Savage is 8.5:1 and the DR is 9.5:1. Will the Savage run ok with a DR cam without a compression increase to 9.5:1? Cam change is a lot faster than a piston change. Thanks |
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Title: Re: DR650 cam on Savage- more compression Required Post by Dave on 04/13/22 at 12:30:15 A cam change can help a bit - in conjunction with a better muffler like a DYNA. You will notice a difference - but it won't be a night/day difference. When you go into the engine to fix a leaky head plug is a good time to swap the cam as well. |
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Title: Re: DR650 cam on Savage- more compression Required Post by wheelbender6 on 04/13/22 at 17:28:18 Thanks. I planned on a gradual approach to more hp. 1st stage - Exhaust, airbox mod and rejet. 2nd stage - Cam, rejet, port match, possibly a 9.5:1 piston. Is Dyna an exhaust brand name or did you mean the stock slip-on for a Harley Dyna? |
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Title: Re: DR650 cam on Savage- more compression Required Post by Dave on 04/13/22 at 19:26:16 647B76767F71767D77766125130 wrote:
I meant a used Harley muffler.....they are cheap used and work well on the Savage. |
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Title: Re: DR650 cam on Savage- more compression Required Post by DragBikeMike on 04/14/22 at 11:07:37 The concern regarding cams vs compression relates to the intake valve closing event. Performance cams usually close the intake valve later. That event occurs after bottom-dead-center (ABDC), when the piston is rising. At lower rpm, the later closing intake valve allows fresh charge to be pushed backwards through the open intake valve. It bleeds off some cylinder pressure and results in lower dynamic compression. To compensate, you can raise the compression ratio. The higher compression restores some of the low-speed torque that is usually lost when a high performance bumpstick is installed. The DR650 cam actually closes the intake valve a little earlier than the stock cam. Low speed performance is not affected at all with the DR cam. It works well with the stock compression ratio. This graph compares the DR intake curve (in red) to the stock intake curve (in black). The data was taken using stock LS rocker arms. |
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Title: Re: DR650 cam on Savage- more compression Required Post by DragBikeMike on 04/14/22 at 11:12:52 The preceding graph depicts the actual position of the valves. Cam manufacturers generally provide lift data taken directly off the cam lobe. They usually use a specific lift point such as .020", .040" or .050". That way a builder can compare one cam to another. This table provides timing data for the stock cam taken directly off the cam lobe. |
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Title: Re: DR650 cam on Savage- more compression Required Post by DragBikeMike on 04/14/22 at 11:13:45 And this table provides timing data for the DR650 cam. |
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Title: Re: DR650 cam on Savage- more compression Required Post by DragBikeMike on 04/14/22 at 11:24:52 You will like the DR650 cam. It runs good. One area of concern is the oil holes in the cam lobes. The DR cam doesn't utilize those holes. I have found that the absence of the holes is not a problem. I have a whole bunch of miles on a standard DR cam (no oil holes) and it holds up well (even with heavy-duty springs). I suggest you use the new-style rocker arms with the brazed cam-follower pads. The DR cam is a simple bolt-in proposition. All the other stock components work perfectly with the DR cam. No need for heavier springs, special spring retainers, cutting guides, etc. Totally plug-n-play. Regarding your selection of compression ratio, the 9.5:1 Wiseco pop-top works good, but the 11:1 Wiseco flat-top works much better. The flat top really amps up the part throttle performance, runs cooler, and yields superb fuel economy, all on 92 octane pump gas. The flat-top runs cleaner too. |
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Title: Re: DR650 cam on Savage- more compression Required Post by wheelbender6 on 04/14/22 at 17:03:46 Thanks DragBikeMike. I can't say I was enthusiastic about swapping a piston. I'm glad the DR cam works good without it. Looks like it will provide about 1000 more rpm, too. -In computer terms, we would say the Savage engine is very "Scalable". The stock engine is affordable and easy to ride, but you can get a good bit more with some straight forward bolt-on mods. Cheers |
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Title: Re: DR650 cam on Savage- more compression Required Post by wheelbender6 on 04/15/22 at 15:42:54 I was watching a video on making a cam change to the Himalayan 411 today. Wow! What a PITA? Far more thrust washers and little bits to keep up with on the Hima. |
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Title: Re: DR650 cam on Savage- more compression Required Post by Dave on 04/16/22 at 03:09:57 564944444D43444F45445317210 wrote:
The Savage engine is pretty basic and pretty easy to work on - one step more primitive and it would have push rods operating the valves......two steps simpler and it would have side valves! With only 30HP - changes that add 1 or 2 HP make a noticeable difference. |
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Title: Re: DR650 cam on Savage- more compression Required Post by Armen on 04/16/22 at 09:03:57 DBM, ‘95 or earlier on the DR cam, correct? Thanks -Armen |
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Title: Re: DR650 cam on Savage- more compression Required Post by LANCER on 04/16/22 at 12:43:34 1990-1995, DR650 Some earlier 600cc Suzuki single engines use the same cam, but you would need to double check to be sure. |
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Title: Re: DR650 cam on Savage- more compression Required Post by Armen on 04/20/22 at 20:19:50 So, what changed on the 96 and later cams that make them NG? Thanks |
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Title: Re: DR650 cam on Savage- more compression Required Post by Fast 650 on 04/21/22 at 00:06:51 I think the bearing sizes are different for the 96 and up. All I know for sure is that it won't fit the LS after the change. |
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Title: Re: DR650 cam on Savage- more compression Required Post by Dave on 04/21/22 at 05:22:14 182B343C37590 wrote:
The design of the head and cam was changed completely and the cams have a decompression device built into the cam. |
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Title: Re: DR650 cam on Savage- more compression Required Post by wheelbender6 on 04/22/22 at 06:10:22 Good to know! :) |
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Title: Re: DR650 cam on Savage- more compression Required Post by Armen on 04/22/22 at 06:47:40 Thanks! |
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