Wreckless_Rider Posted October 19, 2017 Report Share Posted October 19, 2017 What would cause the left rod to snap clean in half and send it thru the top and bottom cases, and the right rod to be bent into an S shape? No blueing around the snapped rod, so it didmt get hot. Bought the bike this way, so not sure what octane they were running. I and am in the process of building a new motor now. Its stock head, looks like they used RTV as a base gasket, +6 timing at the plate, dynatek FS set to "stock" curve, plugs look coffee brown, so it wasnt running lean. Im thinking too much timing @ +6 at the plate with the dynatek on top of that? And probably only ran 87 octane cuz guy i got it from couldnt even tell me what kimda pipes it had, when the tag clearly says pro circuit. So i dont think he was smart enough to use atleast 93 octane. And how about the non existant base gasket? That would raise compression also? I think too much timing, higher compression, and using wrong octane? Sound about right? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted October 19, 2017 Report Share Posted October 19, 2017 I'd say you're assumptions about the excessive timing, compression, and fuel all played a role in that kind of catastrophe. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted October 19, 2017 Report Share Posted October 19, 2017 What about a hydro lock, I've seen alleged hydro lock snap a rod. I bought a parts bike that supposedly went swimming and the rod was snapped clean in half. This was fourth party info so I'm not real sure how credible it was Quote Link to comment Share on other sites More sharing options...
ZillaFreak Posted October 19, 2017 Report Share Posted October 19, 2017 59 minutes ago, sleeper06 said: What about a hydro lock, I've seen alleged hydro lock snap a rod. I bought a parts bike that supposedly went swimming and the rod was snapped clean in half. This was fourth party info so I'm not real sure how credible it was This. Most likely, the idiot left the gas on, it leaked into the carb, then into the bottom end. It flooded. The guy couldn't start it so he pull started it, and hydro locked the end and broke everything. Quote Link to comment Share on other sites More sharing options...
blowit Posted October 19, 2017 Report Share Posted October 19, 2017 My guess, and only a guess is the engine was likely running and got in some water. Unlikely there was enough energy by dragging the bike to not only bend a rod, but snap another and send it through the case. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted October 19, 2017 Report Share Posted October 19, 2017 The poster was worried about timing from a dyna doing that . I've put some pretty ridiculous timing into these things with a curve maker and a plate just playing around. I've never snapped a rod Quote Link to comment Share on other sites More sharing options...
Wreckless_Rider Posted October 20, 2017 Author Report Share Posted October 20, 2017 Honestly im just worried about running this dyna on stock curve with the plate at +4 because some have told me dyna's stock setting is exactly like the factory curve, but then other have told me it still adding timing. I looked at dyna's curve graph and the factory one and there identical except its final timing at 10,000rpm is 4* advanced. Now one the other hand, there was no water in the trans oil, and pieces of the case everywhere. No doubt this thing went while previous idiot was pinning it. Just dont know if it was from timing issue or plain stupidity. And i highly doubt pull starting the bike while its full of gas would send the rod thru top and bottom cases, punching a hole in the bottom of the left cylinder head so hard that it shattered the reed cage. Quote Link to comment Share on other sites More sharing options...
blowit Posted October 20, 2017 Report Share Posted October 20, 2017 Sort of doubt timing did all that. Usually the pistons will nuke or head gasket will let go before rods snap. A rod bent in an S is telltale of trying to compress a liquid. You don;t have to drown one to hydrolock. A good mouth full at 10k rpm is all it takes. Hard to say but on the timing, you have to understand there is a spark "curve" and there is initial advance. When you turn the plate, you are increasing initial advance which moves the entire curve up XX*. I think the Dyna can be set up to be just like factory OR add initial advance but otherwise run the factory curve, if that makes sense. Quote Link to comment Share on other sites More sharing options...
JUSTWANNARACE Posted October 20, 2017 Report Share Posted October 20, 2017 Seen it many times.. cyls fill with fuel, kick it over rods bend, finally get it started take it for a ride, couple min in bent rod breaks and destroys cases. Never seen a rod break from a timing issue and if it did it's cause the bearings failed first from deto.. jmo Quote Link to comment Share on other sites More sharing options...
registered user Posted October 20, 2017 Report Share Posted October 20, 2017 there was no base gasket and maybe head was shaved to much. lets the head and piston top. Quote Link to comment Share on other sites More sharing options...
Wreckless_Rider Posted October 20, 2017 Author Report Share Posted October 20, 2017 I dont know what they did he just said "it just slowly shut off like it ran out of fuel". I saw the cases and knew he was lying lol. Definetly did not slowly die the bitch locked at 10k rpm proly. The dyna's "stock" curve has roughly 3-4* more advance thruout the entire curve past 3600rpm. According to the graph dyna provides on there pdf for this specific box, and the graph provided in the yamaha service manual. Now, that being said, will adding +4 at the plate hurt my top end performance? It will technically be +4* to about 3600rpm, then be +7-8* advance after that. Quote Link to comment Share on other sites More sharing options...
JUSTWANNARACE Posted October 20, 2017 Report Share Posted October 20, 2017 Every motor is going to be different on what it wants for optimal timing. Best thing to do is start low on the timing and slowly increase till you get the timing heat on the plugs where you want it. Pump gas dune bike I like to see the timing burn around 4-5 o'clock and 7-8 o'clock.. alky drag motor just a little less than 3 and 9 o'clock. Jmo Quote Link to comment Share on other sites More sharing options...
JUSTWANNARACE Posted October 20, 2017 Report Share Posted October 20, 2017 Also watch the fuel burn on the porcelain, as you turn the timing up, it may warrant more fuel Quote Link to comment Share on other sites More sharing options...
Wreckless_Rider Posted October 21, 2017 Author Report Share Posted October 21, 2017 Could you explain more to me on "look at the timing heat on the plugs" please? Quote Link to comment Share on other sites More sharing options...
Wreckless_Rider Posted October 21, 2017 Author Report Share Posted October 21, 2017 Also, if i unplug the curve selector box, it defaults the box to the "stock" curve. Now if i do that and run +4 at the plate, i will be +4* up to 3600rpm, then +7-8* up to 10k rpm. Correct me if im wrong, and i most likely am, (im here to learn fellas lol) you want the timing to retard with high rpm? So +8* might hurt my top end performance??? Or i am totally wrong and i will gain twice as much power with +8 then with +4 lol. Keep in mine i do not have access to any fuel higher then 93 octane. And will be keeping stock bore, stock stroke, and stock compression, with dune ported cylinders. 60ft. Above sea level. Quote Link to comment Share on other sites More sharing options...
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