just curious is there a chain readily available already the right length or are people having custom chains cut. anybody know the length on a +4 swing arm?
well, they say a banshee chain will work and that's what my buddy has on his +4. however, i dunno if it's the best option because he has very little adjustment now.
I just recently bought a chain for a +3, I do not use an o-ring as they slightly rob horsepower and the blaster does not have much to start. I got a D.I.D. ERT2 and they come in 120 or 110 link sizes which are both bigger than you need for a blaster +4. Stock chain is 92 links. In this case you can cut the chain or use a chain breaker to get it to exact size you need. I would recommend this chain over any o-ring/x-ring. I would also adjust carrier all the way in when you cut chain and as it stretches slightly adjust out.
the problem with your question is that every builders swinger jig is different, some that have adapted their from a banshee setup, might be off by 1/4 inch either way and that could mean +/- links.
Just buy 110 links of more and you should be happy. Unless of course your running a 15 tooth front and 45 tooth rear